Siege Dragon

You may have this creature enter as a copy of a creature you control, except it has "2UU: Return this creature to its owner's hand."

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.