Elder Gargaroth The only downside to Elder Gargaroth is that it dies to Doom Blade. It needs to attack or block once to provide card advantage, but its a nightmare against aggro and midrange decks because its massive and lets you choose between life, a creature, or a card
Its a lot of fun and Ive had a lot of laughs in games where this card shows up
If Exit Specialist becomes blocked while it's face-down, turning it face up won't cause it to become unblocked
But, even if they never culminate in that, I expect to see these cards frequently in the coming years.
Swords to Plowshares is a great removal for creatures, for example, but a Commander deck with Titania, Protector of Argoth won't be able to use it
Ruthless Technomancer also serves as a good inclusion in a deck looking to harness these effects, as it will actually convert your sacrificed creatures power into Treasure tokens that you can save for a later turn, or simply cash in for an instant speed reanimation effect