Mage.

Proof nr 1: arcane-looking gun

Proof nr 2: Reno is mentioned in Yogg puzzle box flavour text

Proof nr 3: this artwork

Proofs for Finley beeing paladin:
1. Golden weapon

2. Murloc tribe is popular in paladin

Quote From Lightspoon

Metallica won't even have sense since Warlock's HP is to draw a card.

I think this is about "deal 2 damage" part.

Maybe not all 9 portraits, but one of your choice. To keep it exclusive.

Swarming warlock with Recycling is insane synergy.