2.91 Serena (300 rating)

[dejvo]

Serena
4x Nightshade
2x Champion of Irum
2x Aldon the Brave
4x Night Owl
4x Midnight Sentinel
2x Oliver Fagin

3x Garth's Concoction
3x Stop, Thief!

3x Black Garb
4x Ill-Gotten Gains
2x Spirit Shuriken
3x Anklebreaker
4x Thoughtripper's Cutlass

No groundbreaking stuff, but works in current elemental infested meta. It got me from 270 to 302, I think that is as high as it can get.

I started to play Serena to test a theory - she always steals the card you need most, and it really looks like it, though I expected more rage quits. The main pain point of Serena is that she's slow, which is a pain, that's why I made sure to be able to have an ally on board T3 latest. Nightshade+Midnight Sentinel is great combo, if you cast Aldon or another Sentinel you got 3attack with ambush which is what you need.
Match-up with Prax may be the thoughest if he discards card you need. What really works is to cast Black Garb, which stalls him and then next turn cast Shuriken, kill strongest ally with Shuriken's ability, kill another ally with Black garb (or use Garth's Concoction). The goal to beating elementals is to kill their draw with Serena's ability.

Cards that can be changed:
Champ of Irum - I have him just to increase chances to cast an ally in T2, he's pretty good meat shield, as he will be targeted as soon as he's on board.
Garth's Concoction - helpful if you're second and your opponent has 2 allies in T3 and you have nothing. I discard it most of the games, maybe only two are needed and one more Black Garb.

[Cossack Mamai]

Don't you think that Skilled Ironmonger is more useful than Champion of Irum? For example: T3 Black Garb, T4 Ironmonger (+1 durability to Black Garb)

[dejvo]

Black Garb on T3 is not my preferred move, better cast an ally or Garth's Concoction. Also the right play for T4 is most of the time IGG as you need draw, in T5 ideal play is to cast Cutlass (Stop, Thief if you're playing against weapon based hero), so I usually bring out Black Garb on T7 or later. Ironmonger would be still usable though, but I included Champ because I feel I need to drop something on T2 and Ironmonger would be a waste most likely. Now that 2.92 is out and elementals will get slower I might consider change.