Corrupt Data

Whenever you sacrifice a creature, target opponent may sacrifice a creature. If they don't, put a charge counter on this.

At the beginning of your post combat main phase, add {b} and/or {r} for each charge counter on this.

Remove a charge counter: draw a card

Rousing Refrain

Add {R} for each card in target opponent's hand. Until end of turn, you don't lose this mana as steps and phases end. Exile Rousing Refrain with three time counters on it.
Suspend 3—{1}{R} (Rather than cast this card from your hand, you may pay {1}{R} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Crimson Lightning

As an additional cost, sacrifice a creature.

This deals X damage to any target and you create X tapped treasures, where X is the power of the sacrificed creature.

Data Transfer

Move all counters from target creature onto another target creature.

Forced Digivolution

At the beginning of combat on your turn, you may exile target creature you control. If you do, reveal cards from the top of your library until you reveal a creature card and put it onto the battlefield. It gains haste and "At the beginning of the next end step, return this creature to its owner's hand." Return the exiled card to the battlefield tapped under your control at the beginning of the next end step.

Devimon, Black Gear Master

Flying

Whenever this creature attacks and isn't blocked, you may put a gear counter on up to three target creatures defending player controls. If you do, this creature assigns no combat damage this turn.

At the beginning of each upkeep, you may pay {U/R}{U/R}. If you do, gain control of target creature you don't control with a gear counter on it for as long as it has a gear counter on it. If you do, untap it and it gets haste.

Inspiring Refrain

Draw two cards. Exile Inspiring Refrain with three time counters on it.
Suspend 3—{2}{U} (Rather than cast this card from your hand, you may pay {2}{U} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

VenomMyotismon

Vigilance, Reach, Trample, Venomous 2

Sacrifice another creature: choose one - 
• Draw a card and lose 2 life
• This creature deals 2 damage to target creature

Myotismon, Schemer

Flying

Whenever another creature you control dies, exile the top card of your library. You may play that card until the end of your next turn.

When this creature dies, return it to the battlefield tapped and transformed under its owner's control.