Hello All!

This is the deck I used to experiment with health and attack mechanics in Hearthstone.   While it provides a number of intriguing combinations I would advise against trying to run it, even in Casual.  I recall winning only a single game with this terrible thing and that is was certainly sheer luck.  The taunt minions are to keep the opponent (generally the Innkeeper with normal Druid ) off my back so I can run the combos.  The Mind Control was for certain times that the opponent had a minion that would work for my experiments (and I do mean experiments Crazed Alchemist) .

Anyway it gave me some great insight into the game mechanics and I'm sure confused the heck out of some players who encountered me.

In-Depth Guide: Health and Attack in Hearthstone

This guide will attempt to cover a majority of the topics related to the health and attack attributes of the minions including how the effects interact with each other. It is intended primarily as a reference but also to develop a sense of what will happen when these scenarios surface in a game. The information was compiled through observations made with a specialized deck played against real opponents, computer opponents and a dummy account which allowed me to control both players.  The goal was to set up scenarios, log the observations and then develop a model that represents the behavior of the game code. 

Health and Attack Basics

Base Attack and Health: The base attack and health of a minion are displayed on that minion's card.  These are the values which the minion has prior to any effects being played and when all effects are removed. Keep in mind that some minions like Lightspawn have text which modifies the health upon being cast. There is only one effect which can change a card's base value and that is Transformation.  All other effects can be removed through various means. These values are important because they help determine the coloration of the values in the game.

Attack Color: There are 2 possible colors for a minion's attack value:
White - The attack of the minion is unmodified or is lowered below the base value by some effect or combinations of effects.
Green - The attack of the minion is increased beyond it's base value by some effect or combination of effects.

Health Color: There are 3 possible colors for a minion's health value:
White - The health of the minion is full. This includes if it was reduced from the base value by some effect but still at the current maximum.
Red - The health of the minion is less than full, regardless of any effects. The minion is considered 'damaged'. The game remembers how much capacity remains for healing, even if other effects are applied.
Green - The health of the minion is both full and above the base value.

Card Effects

The cards in Hearthstone have effects which modify the health and/or attack of the minions. Some of the effects are an inherent attribute of the minion, others are bestowed as a spell. Some take the form of a battlecry or deathrattle.  There are also effects which are bestowed upon minions from the mere presence of other minions on the battlefield.  In order to develop the model for the health and attack system I have grouped these effects into 5 types which are described below.

1. Transfrom: A few cards have an effect which transforms a minion into a different one. This transformation changes the card into a different one, obliterating all effects. The base value for the attack and health are determined by the new card. A transformation is not really an effect. The mechanic is that the card is immediately replaced with another card - all effects are lost. Four such cards in the game are transformations:

Hex
Polymorph
Poultryizer
Tinkmaster Overspark

2. Instantaneous Effects: These effects are applied by spell, battlecry, deathrattle, or secret. They are applied at a single point in time and alter the minion's values only once. The majority of effects fall in this category so I didn't bother to list them individually. There are a few which are special that I will go into detail about later.

Change - Change is an Instantaneous Effect which modifies a minions health or attack to a set value. Most of them set either health or attack to 1 while one card sets attack to be equal to current (and not maximum) health. These cards are significant because they  'wipe out' all previous effects including Temporary Effects (see #5 below).  Additional effects may be applied afterwards.  There are 5 cards in the game with the word 'change' on them:

Hunter's Mark
Humility
Equality
Aldor Peacekeeper
Inner Fire

3. Cumulative Effects - These effects can be applied more than once within a game from a source which is cast a single time. They can be applied both before and after other effects. For example if Hunter's Mark is applied to a minion which had been buffed by Young Priestess, the Priestess may continue to increase the health beyond 1. There are 18 cards that belong to this type:

Mana Wyrm
Scavenging Hyena
Unbound Elemental
Blood Imp
Frothing Berserker
Murloc Tidecaller
Secretkeeper
Undertaker
Young Priestess
Master Swordsmith
Flesheating Ghoul
Questing Adventurer
Shade of Naxxramas
Gruul
Ethereal Arcanist
Lightwarden
Gurubashi Berserker
Emboldener 3000

4. Persistent Effects: These effects persist while certain conditions are met, typically the presence of the granting minion. They may apply to a single minion or multiple minions. It is possible for minions who are summoned later to immediately benefit from the effect. They can impact both health and attack. There are other persistent effects in the game but only the nine which affect health or attack are listed here:

Timber Wolf
Grimscale Oracle
Dire Wolf Alpha
Murloc Warleader
Raid Leader
Southsea Captain
Old Murk-Eye
Stormwind Champion
Flametongue Totem

Enrage - Enrage is a Persistent Effect that is present while the minion is damaged. Other than Spiteful Smith, Enrage only impacts the enraged minion and only affects attack. I did not include the Spiteful Smith in the list because his enrage only impacts the hero and not a minion. The five minions with Enrage are:

Raging Worgen
Amani Berserker
Angry Chicken
Tauren Warrior
Grommash Hellscream

5. Temporary Effects: These effects are valid only for a set period of time after being cast. The duration is until the end of the turn for all but one which continues until the start of the players next turn. These effects work like Instantaneous Effects except that they have special interaction with certain cards, namely the 'change' cards mentioned above and the  Crazed Alchemist which will be discussed later. There are nine cards which grant health or attack effects:

Savage Roar
Bestial Wrath
Abusive Sergeant
Mana Addict
Dark Iron Dwarf
Rockbiter Weapon
Bloodlust
Power Overwhelming
Nightmare

Special Card Effects

Before I get into how the health and attack are computed I need to cover some effects which have special rules and interaction.

Divine Spirit: This card is an Instantaneous Effect which will 'double' the health of a minion. More specifically, the current displayed health is added to the maximum. Any damage taken is ignored.

Example 1 - Say a Northshire Cleric (1/3) is buffed with Power Word: Shield (now 1/5) and then damaged by the Mage Hero Power (now 1/4). The Divine Spirit is cast on it resulting in the card reading 1/8 with the 8 in red. If healed to maximum the card will display 1/9 with the 9 in green.  Had the Divine Spirit been applied prior to the Mage's attack, the minion would have become a 1/10 instead.

Example 2 - Say the same Northshire Cleric (1/3) was joined by a Stormwind Champion (now 2/4). When Divine Spirit is cast on the Northshire Cleric the result is the card reading 2/8 with the 8 in green. Now say the Stormwind Champion is turned into a frog by a Shaman's Hex spell. The Northshire Cleric loses the benefit from the Stormwind Champion but retains the effects of Divine Spirit and bcomes a 1/7. In other words, Persistent effects are doubled.  It is not clear if Temporary Effects are doubled as well, but since all Temporary Effects which raise health result in the death of the minion I did not investigate this.

Lightspawn - This 0/5 Priest minion is special because it's card text overrides any and all effects to minion attack value. The attack always matches the health. It gains no benefit from standing by a Dire Wolf Alpha, nor is it affected by the abuse of the Abusive Sergeant. When your other minions are whipped into a frenzy from a stolen Bloodlust, the Lightspawn is not affected. The only time it's attack can be different is when the original card text is slienced. Then its attack reverts to zero and effects may be applied as normal. With its text intact, this minion is not affected in any way by Inner Fire or Crazed Alchemist.

Crazed Alchemist: This confusing card has a battlecry which swaps the health and attack of a minion. While this may seem simple at first there are some caveats with respect to how it operates. The first caveat is that Temporary Effects are considered into the result, but the
temporary effects are not applied again after the swap nor do the values revert when the temporary effect expires. If your minion was increased from 1/4 to 3/4 under the effect of Abusive Sergeant, it becomes a 4/3 and remains a 4/3 when the turn is over. Some people describe this as making the change 'permanent'. The other caveat is that Persistent Effects not only are considered into the result, but are re-applied after the swap! Two examples from actual gameplay follow.

Example 1 - A Young Priestess enters the battlefield with a Stormwind Champion already present. Her stats are immediately increased from 2/1 to 3/2. The Crazed Alchemist targets her with the battlecry and she becomes a 3/4. The stats were swapped from 3/2 to 2/3 and then the Stormwind Champion buff was reapplied. Crazy!

Example 2 - A player researching health stats wants to see if he can 'kill' a minion by removing a Persistent Effect from play. He summons a Shieldbearer with a Stormwind Champion already present resulting in a 1/5 Shieldbearer. Crazed Alchemist targets the Shieldbearer and he becomes a 6/2, thus thwarting the player's attempt to 'kill' a minion by silencing another.

Computation of Health and Attack

Based on the various effects and the observations made it is possible to determine the algorithm used to compute the health and attack value of a minion.

The first thing to keep in mind is that effects may not be implemented exactly the way the card states. When talking about which deathrattle happens first, which secret triggers first, or which minion gets targeted by Duplicate in a board wipe, the prevailing guidance is first cast first resolved. With health and attack buffs, this is not the case. For each class of effects, the commutative property applies - order does not matter.

As effects are cast on a minion, each effect is added to the scroll at the bottom of the card. Young Priestess adds Elune's Grace. Power Word: Shield adds a buff. It really doesn't matter how you add them up.  What about Hunter's Mark you say - it clearly negates all previous effects and sets health to 1.  This may be true, but then how does a further addition of health by the Young Priestess increases the minion's health after Hunter's Mark if the Elune's Grace appears prior to Hunter's Mark in the cast order? The answer is simple. Hunter's Mark does not set a minion's health to 1 - it reduces maximum health by one less than maximum health.  For example if the minion's current health was 12 (Deathwing), it is a -11 buff to health. This way the cast order doesn't matter.  Divine Spirit, the other 'change' cards, and Crazed Alchemist work the same way.

After the Instantaneous, Cumulative, and Temporary effects are applied, the Persistent effects are applied in the same manner. This is why using Humility on minion which is next to a Dire Wolf Alpha results in an attack of 2, not 1.

The only other thing to consider is the elimination of Temporary Effects. If a minion has been buffed with a Temporary Effect and is then subject to a Divine Spirit, Crazed Alchemist, or 'change' card, the Temporary Effects are not added. My theory is that there is a hidden temporary debuff added to the minion by these cards.

To summarize, the formula is that all effects are computed in groups starting with Instantaneous and Cumulative Effects, then Temporary Effects so long as no 'special' or 'change' cards have invalidated them, and last Persistent Effects. Order of each individual effect does not matter but if it is easier to keep track of it that way, then that works as well.

Current Health and Removal of Effects

I won't go into too much detail about this topic because it is covered in other guides but when a minion's maximum health is changed because it is silenced,  a Persistent Effect is removed, or  a new effect results in a decrease, one of two things happens:

• If the current health is above the new maximum value then the current health is lowered to the new maximum value.
• If the current health is at or below the new maximum value, the current health is not modified. 

It is not possible to kill a minion by removing an effect, however, the Crazed Alchemist can kill 0/X minions with his battlecry.

Well that's it thanks for reading and hope you liked my guide - happy playing and may the RNG be ever in your favor!