Boros Reckoner

Whenever Boros Reckoner is dealt damage, it deals that much damage to any target.
{R/W}: Boros Reckoner gains first strike until end of turn.

Plains

Eye for an Eye

The next time a source of your choice would deal damage to you this turn, instead that source deals that much damage to you and Eye for an Eye deals that much damage to that source's controller.

Truefire Captain

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Truefire Captain is dealt damage, it deals that much damage to target player.

Spiteful Sliver

Sliver creatures you control have "Whenever this creature is dealt damage, it deals that much damage to target player or planeswalker."

Invulnerability

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
The next time a source of your choice would deal damage to you this turn, prevent that damage.

Reflect Damage

The next time a source of your choice would deal damage this turn, that damage is dealt to that source's controller instead.

Deflecting Palm

The next time a source of your choice would deal damage to you this turn, prevent that damage. If damage is prevented this way, Deflecting Palm deals that much damage to that source's controller.