Please keep in mind that this is all speculation, we don't actually know the rules yet and there hasn't been any explanation from official sources on how this works
His ability to prevent effect-based removal and cycle cards makes him a key piece for players who appreciate board presence
However, you may do so only during one of your main phases when the stack is empty
Soltari Priest (Ext, S, Block) The best shadow creature in the Magic game, hands down
If you do, create two 1/1 black and red Goblin creature tokens
Since the most dangerous weenie creatures in Standard are white and green, Self-Inflicted Wound will be a valuable sideboard tool, if not a main-deck consideration