Hearthpwn

This is probably my favourite of the finalists. Decay's not that bad of a custom keyword, the hero power's good, you've got well established themes and the card quality is very high. I've got a little feedback but I think most of the cards you can still update are fine.

I think you should upscale Gnomechanic. As a 1 mana minion with a reward also worth about 1 mana, I think it's still a fairly disappointing thing to draw later on in the game, despite only working later on in the game.

I think mechanically your Rumble set works well, but I'm not sure I'm getting enough Jani vibes from it, feels maybe a bit too generic. The flavour on most of the cards points to the arena, dueling, combat etc, but there's very little on scavenging, trash, or other prominent Jani themes.

I think your Boomsday theme is fine but maybe Shuffl-o-Tron is a bit too direct.

Hope you win.