Gigantomancer

{1}: Target creature you control has base power and toughness 7/7 until end of turn.

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Ziatora, the Incinerator

Flying
At the beginning of your end step, you may sacrifice another creature. When you do, Ziatora, the Incinerator deals damage equal to that creature's power to any target and you create three Treasure tokens.

Yargle and Multani

Star of Extinction

Destroy target land. Star of Extinction deals 20 damage to each creature and each planeswalker.

Yargle, Glutton of Urborg

Exponential Growth

Until end of turn, double target creature's power X times.

Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample

Damnation

Destroy all creatures. They can't be regenerated.

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Hydra's Growth

Enchant creature
When Hydra's Growth enters, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Juri, Master of the Revue

Whenever you sacrifice a permanent, put a +1/+1 counter on Juri, Master of the Revue.
When Juri dies, it deals damage equal to its power to any target.