Xenagos, God of Revels

Indestructible
As long as your devotion to red and green is less than seven, Xenagos isn't a creature.
At the beginning of combat on your turn, another target creature you control gains haste and gets +X/+X until end of turn, where X is that creature's power.

Barrage Tyrant

Devoid (This card has no color.)
{2}{R}, Sacrifice another colorless creature: This creature deals damage equal to the sacrificed creature's power to any target.

Soul's Fire

Target creature you control deals damage equal to its power to any target.

Repercussion

Whenever a creature is dealt damage, this enchantment deals that much damage to that creature's controller.

Juri, Master of the Revue

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

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on this creature.

Bulk Up

Double target creature's power until end of turn.
Flashback {4}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Daemogoth Titan

Whenever this creature attacks or blocks, sacrifice a creature.

Bloodshot Cyclops

{T}, Sacrifice a creature: This creature deals damage equal to the sacrificed creature's power to any target.

Jumbo Cactuar

10,000 Needles — Whenever this creature attacks, it gets +9999/+0 until end of turn.

Freyalise Supplicant

{T}, Sacrifice a red or white creature: This creature deals damage to any target equal to half the sacrificed creature's power, rounded down.

Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Unleash Fury

Double the power of target creature until end of turn.

Thud

As an additional cost to cast this spell, sacrifice a creature.
Thud deals damage equal to the sacrificed creature's power to any target.

Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Mr. Orfeo, the Boulder

Whenever you attack, double target creature's power until end of turn.

Heart-Piercer Manticore

When this creature enters, you may sacrifice another creature. When you do, this creature deals damage equal to that creature's power to any target.
Embalm {5}{R} ({5}{R}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Manticore with no mana cost. Embalm only as a sorcery.)

Pyrrhic Blast

As an additional cost to cast this spell, sacrifice a creature.
Pyrrhic Blast deals damage equal to the sacrificed creature's power to any target. Draw a card.

Ziatora, the Incinerator

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

Surtland Flinger

Whenever this creature attacks, you may sacrifice another creature. When you do, this creature deals damage equal to the sacrificed creature's power to any target. If the sacrificed creature was a Giant, this creature deals twice that much damage instead.

Coram, the Undertaker

Coram gets +X/+0, where X is the greatest power among creature cards in all graveyards.
Whenever Coram attacks, each player mills a card.
During each of your turns, you may play a land and cast a spell from among cards in graveyards that were put there from libraries this turn.

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.