Hmm... Well it's 4 mana and two cards to cast two 2/2 Kobolds each with Spell Damage +1, and a card is usually worth ~2 mana, so a 4/4 minion with Spell Damage +2 should cost around 6 mana. Now, Spell Damage is an ability that's worth more the lower the minion's cost is because a lower-cost minion means you have more mana left over to make use of the Spell Damage on the same turn. This same principle should apply to higher amounts of Spell Damage, and I personally don't think that a Spell Damage +2 minion should ever cost less than 5. So, a 5-mana 3/3 with Spell Damage +2 might be about right.
You could even try an OTK deck.. (which is bad for the game, hence i dont think they want to add +2 spell damage into the game) you play the weapon a turn in advance, then next turn you play 2 minions + ancient mage. You now have 4spell damage. 2 bolt + 2 lance is exactly 30 damage.
I do not believe so. Look at Innervate, for example, or Preparation (which gets more discount but has more of a restriction on how it can be used). Also look at how 2-cost Hero Powers (which do not cost a card) are basically the equivalent of 0-cost cards (Fireblast is like Moonfire, Reinforce is like Wisp, etc.)
Look at Dalaran Mage. 4 mana 3/5 is normal, you pay a 4 mana 2/5 for +2 spell damage.
Not exactly. First of all, vanilla stats for a 4-cost minion is 4/5, not 3/5. See Chillwind Yeti. 3/5's for (4), like Violet Teacher, are already allowed additional effects. Second, Ancient Mage's +2 Spell Damage is conditional on you already having two minions. Effects that are conditional on your having minions in play get discounts because of that. We don't, for example, consider Flametongue Totem to be equivalent to a 4/3 for 2, and we also don't consider Defender of Argus to be equivalent to a 4/5 for 4 with... I guess double-taunt?
Anyway, we're not discussing a conditional +2 Spell Damage here like we already have with Dalaran Mage. We're discussing a minion that simple has Spell Damage +2.
There is a line that seperates what is meta viable and complete crap, and a 3/3 for 5 is complete crap.
Not if the card text effect is good enough. I see plenty of people playing and appreciating Antique Healbot.
Malygos spell damage +5. 9 mana 4/12 4 + 12 = 16 16/2 = 8. Sacrificed 1 mana for spell damage +5. By that logic a 5 mana 3/3 could also be spell damage +5 and legendary.
The problem with Malygos is that you can't play enough spells the same turn as you play it to really take advantage of it most of the time. That's why Bloodmage Thalnos is and will always be a far more popular legendary than Malygos. In other words, Malygos has a built-in limiter to its apparent power, and that's why using it to work out what value of different spell damage amounts should be doesn't quite work. It doesn't take into account that the higher-cost mana a creature is, the less the Spell Damage on it is worth because you have less ability to take advantage of that spell damage. Do you know how ridiculous a 5 mana minion with Spell Damage +5 would be? No joke, it could be a 0/1 and break the game. I'm pretty sure most classes could near-OTK with that easily.
If you're asking "Can they just put a +2 Spellpower minion in the game" the answer is assuredly "yes" as there's already a) a minion with +5 and b) there's a minion with theoretically +2 (+) Spell Power. The real question is "What would that be worth stat wise and how could it be implemented as balance."
Spellpower is one of the harder keywords to definie in terms of mana value as it's not as static as "Taunt" or "Windfury" or "Charge". One could make the argument that +1 Spellpower appears to be worth ~ 1 stat point - i.e. Kobold Geomancer versus the variety of vanilla 2/3 and 3/2 for 2 mana, and Ogre Magi compared to Chillwind Yeti. The problem is that +2 would likely be worth more than 2 stats though as the potential snowball effect of +2 Spellpower compared to +1 isn't really the 1:1 comparison it might appear to be. In other words, I don't think you could say 4 mana 3/4 +2 Spellpower is fair even though that's -2 stats compared to accepted vanilla baseline for 4 mana.
Hmm... Well it's 4 mana and two cards to cast two 2/2 Kobolds each with Spell Damage +1, and a card is usually worth ~2 mana, so a 4/4 minion with Spell Damage +2 should cost around 6 mana. Now, Spell Damage is an ability that's worth more the lower the minion's cost is because a lower-cost minion means you have more mana left over to make use of the Spell Damage on the same turn. This same principle should apply to higher amounts of Spell Damage, and I personally don't think that a Spell Damage +2 minion should ever cost less than 5. So, a 5-mana 3/3 with Spell Damage +2 might be about right
.Sorry for writing here, cuz phone. What examples do you have about two card effects on one card being worth 2 mana? Belcher? Implosion? Cairne?