Anowon, the Ruin Thief is a Rogue lord, giving all rogues +1/+1. His other ability gives you card advantage while also milling your opponents decks out
Stack up five Treasure tokens, and suddenly you get to tutor any dragon or artifact straight onto the battlefield, which can lead to some absurdly explosive mid-game turns
You also get to dish out poison counters when it deals damage, which can close out a game very quickly
Why its helpful Characters with the Challenger trait are most effective when they initiate a fight
These enchantments gain quest counters from certain triggers, and after collecting four, provide an effect for those triggers
For all of the details about these amazing folks, I recommend checking out Mark Rosewater's article today