Kefnet the Mindful

Change the target of target spell with a single target unless that spell's controller pays 2.

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost. Counter target spell.

Tap an untapped creature you control: Tap target artifact, creature, or land.

Search your library and graveyard for five cards and exile the rest. Put the chosen cards on top of your library in any order. You lose half your life, rounded up.

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.) Return target permanent to its owner's hand.

Chain Lightning deals 3 damage to any target. Then that player or that permanent's controller may pay RR. If the player does, they may copy this spell and may choose a new target for that copy.

Add BBB.

Return all lands to their owners' hands.