Hearthpwn

I tried to make Dark Portal work since its release, and now it finally does work. It took me from gold to legend with a 60% winrate (72-48)

You have essentially two game plans: playing control lock against aggro ( wincondition eary voidlords, guldan, heal) with a lot of clears and some heal, and playing combo against control.

keep track of your dragons, you only have 4, so you might have to hold one back in addition to malygos for breath activation

Possible damage depends on maly cost, but over 30 is possible without portal or frizz on malygos (if you hit dark bomb, breath, rain of fire, soulfire and malygos with emperor)

Always think about how much damage you will need in a given matchup to decide when to play emperor

valdris is actually better in aggro matchups for refill, and a great portal pull in all matchups

there are many games where you just win with a discounted alex and burn from hand/ with a board and some burn.

Against aggro, forget about maly combo and play for survival, you usually win if you get to guldan (or cheat voidlord on 4). maly can be great heal with a single breath.

Some matchups:

Quest mage: difficult to play, you have two ways of winning: comboing faster or draining them of ressorces and stopping them from killing you with voidlords+guldan. depends on the game and your hand.

Druid: always mulligan for aggro, since its more common and you lose hard without early clear and early voidlord. Control/combo druid is highly unfavoured, you need to get chip damage through and keep their armor below 15, so alex can set them to 30 (15 life/15 armor)

Secret mage: favoured! 88% winrate, mulligan for voidcallers, clears and nether breath

reno priest: favoured! 83% winrate, mulligan for frizz dark portal, keep sense demons if you have a portal to thin the pool. you just kill them faster if you do not lowroll

paladin is an even matchup, against odd you need to trigger their secret as soon as possible (eg soul shear a dude on 2) since you lose if you cannot get your defile to connect. voidlord is often gg. clear their board every turn (at least if you are afraid of them buffing it next turn) netherwing is great as it doesnt trigger the secret. libram is not common, you need dark skies early and maybe even maly in the late game. nether can win 

warrior: if you get your clears, you should destroy pirate warrior. other warrior decks are nearly non existent

dh is a bad matchup, but i didnt encounter many of them. mulligan for breath and voidcaller/voidlord/sac pac/sense demons + clears, pray for them not having silence

hunter: bad matchup. you die to heropower to fast

rouge: 50/50, depends on their start. taunt is the way to go against odd, kingsbane is a horrible matchup if they highroll, since you cannot run weapon tech and they have sap

shaman: not many of them, mostly even. 50/50 matchup, depening on your clears and how fast they get big minions down. dark skies is mvp, you might need nether in the late game

warlock slightly favoured (if they get early skull, you lose). reno is a good matchup, cube is bad, if they get a good start they stomp you, if not, you often need only 18-20 burst against them.

only bad, but winable matchups are those decks wit. high armor gain, but i encountered only one odd warrior and two combo druids (lost those games). most druids are aggro right now, so destroy them with your early game clears.

detailed guide for some upvotes, i will answer questions in the comments

general: