I'm certainly a fan of Icebound Revenant.
There's something fun about just stacking a pile of DOTs on monsters and just watch them wither away while keeping up your defenses.
I also like how it manages to be mostly locked to Ice, but still works as effectively against monsters with ice resistance as any others (A few monsters it takes a penalty against, while others... it's actually better)
The only small issue I have is that it can't force an Ice weakness to monsters with 200 Ice resistance, so it can't make full use of it's abilities there (But then, it can't do that, and sometimes is worse off against things with less Ice res, so hey).
But it has kind of insane damage output against anything it can force the Ice weakness on, which is like, at least 95% of the monsters in the game.
Since a majority of it's damage comes from the DOTs, which just get doubled with any weakness, after you've kept Long Winter going for long enough (I think 25 turns from when you first use it?), the skill alone effectively deals 470%-770% weapon damage (The range kind of depends on the Ice weakness. The bigger the weakness is, the less damage the DOT deals in comparison to your weapon damage proper, if that makes sense), with a really low cooldown.