Mr. Orfeo, the Boulder

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

Indoraptor, the Perfect Hybrid

Bloodthirst X (This creature enters with X +1/+1 counters on it, where X is the damage dealt to your opponents this turn.)
Menace
Enrage — Whenever Indoraptor is dealt damage, choose an opponent at random. Indoraptor deals damage equal to its power to that player unless they sacrifice a nontoken creature of their choice.

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.

Gyrus, Waker of Corpses

Gyrus enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
Whenever Gyrus attacks, you may exile target creature card with lesser power from your graveyard. If you do, create a token that's a copy of that card and that's tapped and attacking. Exile the token at end of combat.

Phytotitan

When this creature dies, return it to the battlefield tapped under its owner's control at the beginning of their next upkeep.

Phoenix Chick

Flying, haste
This creature can't block.
Whenever you attack with three or more creatures, you may pay {R}{R}. If you do, return this card from your graveyard to the battlefield tapped and attacking with a +1/+1 counter on it.

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.