You may pay rather than pay this spell's mana cost.
Trample
At the beginning of your upkeep, you may pay 2 life. If you do, search your library for a card, then shuffle your library and put that card on top of it.

Trample
Provoke (Whenever this creature attacks, you may have target creature defending player controls untap and block it if able.)

As an additional cost to cast this spell, sacrifice a creature.
Target creature gets -X/-X until end of turn, where X is the sacrificed creature's power.

Create a 3/3 green Elephant creature token.
Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)

, : Search your library for a Mercenary permanent card with converted mana cost 3 or less and put it onto the battlefield. Then shuffle your library.

, : Search your library for a Mercenary permanent card with converted mana cost 1 or less and put it onto the battlefield. Then shuffle your library.

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
, : Search your library for a Mercenary permanent card with converted mana cost 5 or less and put it onto the battlefield. Then shuffle your library.

: Target player mills a card.

Return target nonland permanent to its owner's hand. Then that permanent's controller may sacrifice a land. If the player does, they may copy this spell and may choose a new target for that copy.

Destroy target attacking creature. You gain life equal to its power.

Mutate (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Whenever this creature mutates, each opponent sacrifices a creature.

Tap up to four target creatures.
Cycling (, Discard this card: Draw a card.)
When you cycle Choking Tethers, you may tap target creature.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
: Regenerate Cinderbones.

Clockwork Beast enters the battlefield with seven +1/+0 counters on it.
At end of combat, if Clockwork Beast attacked or blocked this combat, remove a +1/+0 counter from it.
, : Put up to X +1/+0 counters on Clockwork Beast. This ability can't cause the total number of +1/+0 counters on Clockwork Beast to be greater than seven. Activate this ability only during your upkeep.

You may have Clone enter the battlefield as a copy of any creature on the battlefield.

Flying
Fading 3 (This creature enters the battlefield with three fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)

: Target creature gets -1/-1 until end of turn. Put a +1/+1 counter on Consumptive Goo.

Flying
, : Crimson Hellkite deals X damage to target creature. Spend only red mana on X.

Crushing Pain deals 6 damage to target creature that was dealt damage this turn.

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)
: Cursed Ronin gets +1/+1 until end of turn.