Mercurial Pretender

When you cast this spell, reveal the top X cards of your library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield. Then shuffle the rest into your library. This creature enters with X +1/+1 counters on it.

Other Goblin creatures you control attack each combat if able. At the beginning of combat on your turn, create a 1/1 red Goblin creature token with haste. Whenever this creature attacks, it gets +1/+0 until end of turn for each other attacking Goblin.

Trample 5: Permanents you control gain indestructible until end of turn. 5, Exile this card from your graveyard: Permanents you control gain indestructible until end of turn.

Destroy all creatures you don't control and all planeswalkers you don't control.

Flying At the beginning of your upkeep, draw a card unless target opponent sacrifices a creature of their choice or pays 3 life.

Flying, trample Whenever an opponent searches their library, that player sacrifices a creature of their choice and loses 10 life. Whenever another creature dies, put a +1/+1 counter on Ob Nixilis.

When this creature enters, you may destroy target artifact or enchantment.

Artifact spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting an artifact spell pays for 1 or one mana of that creature's color.)