Flying When Shadowborn Demon enters the battlefield, destroy target non-Demon creature. At the beginning of your upkeep, if there are fewer than six creature cards in your graveyard, sacrifice a creature.
You may have Glasspool Mimic enter the battlefield as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.
"When I touched the Glasspool, I tasted infinite possibility." —Ashen Wal, Akoum Expeditionary House
Flying Whenever you cast a spell from exile, copy it. You may choose new targets for the copy. If it's a permanent spell, the copy gains haste and "At the beginning of the end step, sacrifice this permanent."
At the beginning of your end step, if a creature died under your control this turn, the Ring tempts you. Whenever the Ring tempts you, target opponent reveals cards from the top of their library until they reveal a land card. Put that card onto the battlefield tapped under your control and the rest into their graveyard.
When Petravark enters the battlefield, exile target land. When Petravark leaves the battlefield, return the exiled card to the battlefield under its owner's control.
Prevent all damage that would be dealt to you by sources you don't control. When a card is put into your graveyard from anywhere, sacrifice Energy Field.
When Springbloom Druid enters the battlefield, you may sacrifice a land. If you do, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
"New growth applies a healing poultice to wounds long scabbed over."
Protection from permanents with corruption counters on them [+1]: Each opponent loses 2 life and you gain 2 life. Put a corruption counter on up to one other target creature or planeswalker. [–3]: Gain control of target creature or planeswalker until end of turn. Untap it and put a corruption counter on it. It gains haste until end of turn. [–7]: Gain control of each permanent with a corruption counter on it.
The Nuka-Cola Challenge — Whenever one or more creatures you control deal combat damage to a player, put a quest counter on Sierra, Nuka's Biggest Fan and create a Food token. Whenever you sacrifice a Food, target creature you control gets +X/+X until end of turn, where X is the number of quest counters on Sierra.