Agent of the Shadow Thieves

Commander creatures you own have "Whenever this creature attacks a player, if no opponent has more life than that player, put a +1/+1 counter on this creature. It gains deathtouch and indestructible until end of turn."

Naturalize

Skullbriar, the Walking Grave

Haste
Whenever Skullbriar, the Walking Grave deals combat damage to a player, put a +1/+1 counter on it.
Counters remain on Skullbriar as it moves to any zone other than a player's hand or library.

Putrefy

Destroy target artifact or creature. It can't be regenerated.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Return to Nature

Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Exile target card from a graveyard.