His conditional indestructibility has the potential to turn off kill cards from decks that dont have early drops or cant keep them on the table, and his recursive potential is unlocked by any deck that either a) plans to use Delve (Tasigur, Angler, Treasure Cruise, Dig Through Time) or b) plans to abuse Deathmist Raptor and Den Protector
The spell also has the added benefit of replacing itself by drawing you a card when it is cast as long as you control at least one merfolk, letting it still maintain its usefulness over the course of a game
Conclusion: Embrace the Power of Elf Commanders in MTG Elves have been a Commander staple since the format began, and thats not changing anytime soon
The best aspect of this creature is that you can grab cards from opponents graveyard, so getting a good enters creature like Ravenous Chupacabra or a creature that makes many tokens is very interesting
What makes Zack Fair a really worthwhile commander is his white color identity