Mikaeus, the Unhallowed + Devoted Druid

Prerequisites

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Steps

1. 1Activate Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
2. 2Repeat step 1 until Devoted Druid dies as a state-based action due to having zero toughness.
3. 3Devoted Druid dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
4. 4Repeat.

Effects

• Infinite death triggers
• Infinite ETB
• Infinite LTB