Approval — When Dampening Reconciliator enters, tap up to one target creature and put X stun counters on it, where X is the number of colors among permanents you control.
“Stay the course, friends. Unrest leads to nothing but a weakened state.”
Vigilance Whenever Dark Ambassador attacks, exile up to one target creature, then return that card to the battlefield tapped under its owner's control.
“I bring the gift of peace, of new life, and abolition of all woes.”
When Data Weaver enters, integrate the top two cards of target opponent's library. Once during each of your turns, you may play a card integrated onto a permanent you control, and mana of any type can be spent to cast it.
Exile all creatures and all cards from each player's hand. Any player may play those cards during their turn for as long as they remain exiled, and mana of any type can be spent to cast those spells. Exile Dawn of Peace.
{6}, {T}, Sacrifice Deafening Loudspeaker: It deals 5 damage to target creature. This ability costs {1} less to activate for each attacking creature you control.
When Deathcap Guardian enters, exile any number of permanent cards from your graveyard. When you do, put X +1/+1 counters on Deathcap Guardian and up to one target creature gets -X/-X until end of turn, where X is the number of cards exiled this way.
You may cast this spell as though it had flash by sacrificing a creature in addition to its other costs. If you do, when it enters, attach it to target creature you control. Equipped creature gets +2/+0 and has “Whenever this creature deals combat damage to a player, that player discards a card.” Equip—Pay 2 life.
You may choose this spell's targets at random. If you do, it costs {2} less to cast. Return target instant or sorcery card from your graveyard to your hand. Flashback {6}{R}
Deepcavern Scyllia enters with X +1/+1 counters on it. You may cast Deepcavern Scyllia from your graveyard by paying {3}{G} and exiling X other permanent cards from your graveyard rather than paying its mana cost.
However many heads it has, you can safely assume it's better than one.