Hawkeye's Bow + Kelpie Guide + North Pole Patrol Combo

All permanents on the battlefield (Hawkeye's Bow attached to either Kelpie Guide or North Pole Patrol on the battlefield and Kelpie Guide and North Pole Patrol without summoning sickness on the battlefield).

Activate Kelpie Guide by tapping it, targeting North Pole Patrol.

If Kelpie Guide has Hawkeye's Bow attached to it, Hawkeye's Bow triggers, dealing 1 damage to each opponent.

Resolve the Kelpie Guide ability, untapping North Pole Patrol.

Activate North Pole Patrol by tapping it, targeting Kelpie Guide.

If North Pole Patrol has Hawkeye's Bow attached to it, Hawkeye's Bow triggers, dealing 1 damage to each opponent.

Resolve the North Pole Patrol ability, untapping Kelpie Guide.

Repeat.

Infinite damage