Ratadrabik of Urborg + Sarkhan, the Dragonspeaker + Goblin Bombardment

Ratadrabik of Urborg

Sarkhan, the Dragonspeaker

Goblin Bombardment

How it works

1. Activate Sarkhan's first loyalty ability by putting a loyalty counter on it, causing it to become a legendary 4/4 Dragon creature with flying, indestructible and haste.
2. Activate Goblin Bombardment by sacrificing Sarkhan.
3. When Sarkhan dies, Ratadrabik triggers, creating a token copy of Sarkhan that isn't legendary.
4. Resolve the Goblin Bombardment ability.
5. Repeat using the Sarkhan token.

This cunning loop turns the planeswalker Sarkhan, the Dragonspeaker into an immortal dragon by leveraging his own [+1] ability to animate him into a legendary creature. Once Sarkhan is vulnerable as a creature, you sacrifice him to Goblin Bombardment to deal damage, which neatly triggers Ratadrabik of Urborg to create a nonlegendary token copy of Sarkhan. Because the resulting token isn't legendary, the cycle can repeat indefinitely as you sacrifice each new iteration of Sarkhan to the Bombardment for an endless storm of damage, deaths, and leaves-the-battlefield triggers.