Well, against lv3 I usually use a darkness deck with 6 devourers and 6 steals to delay the oponent to maximum. Dragons reduce life, and I use drain life to get mastery. Most lv3 decks arent difficult. The darkness entropy one just beat can me when they get the discord in early game. But I usually still win.
The ones that really cause trouble:
- Life and gravity, when get a blessed otyugh in early game.
- Time, when those cursed eggs turn in something like an emerald dragon in first turns.