Lullmage Mentor, and Intruder Alarm

Prerequisites

• Lullmage Mentor on the battlefield
• Intruder Alarm on the battlefield
• You control at least seven Merfolk

Steps

1. Whenever an opponent casts a spell, activate Lullmage Mentor by tapping seven Merfolk you control, countering that spell
2. Lullmage Mentor triggers, creating a 1/1 Merfolk creature token
3. The Merfolk token enters the battlefield, triggering Intruder Alarm, untapping all creatures
4. Repeat

Results

• Counter all spells your opponents cast