Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Kefnet the Mindful

Flying, indestructible
Kefnet the Mindful can’t attack or block unless you have seven or more cards in hand.
: Draw a card, then you may return a land you control to its owner’s hand.

Attrition

, Sacrifice a creature: Destroy target nonblack creature.

Loam Dryad

, Tap an untapped creature you control: Add one mana of any color.