Countdown to victory

Choose a target you can see within 120ft. The target must make a constitution save ( dc 15) upon a failed save roll 3d6+3. The target creature gets that many tokens. While the target creature has tokens when it has tokens it is immune to damage, any time the creature would take damage remove one token instead. At the end of the creature's turn they will also lose one token. When the creature tokens reach zero the creature dies. When you cast this spell using a spell slot of 8th lv or higher the token modifier decreases by 1 for each level above 7. Thank's to Lupin#5264 on discord for helping me make the spell better.