Joven and Chandler [Unknown Event] Masters 25 Search your library for an

Search your library for an artifact card with mana value X or less

you may reveal a creature card from your hand

Prepare your adventurers for a challenging dungeon exploration in Paper Dungeons

It is found here

Joven and Chandler [Unknown Event] Masters 25 Search your library for anSet: Unknown Event Type: Legendary Creature Human Rogue Rarity: Common Backup 2 (When this creature enters the battlefield, put two +1 +1 counters on target creature. If that's another creature, it gains the following abilities until end of turn.) Haste Whenever this creature deals combat damage to an opponent, destroy target artifact that player controls.