Enchantment (CMC 3)
At the beginning of the end step, if no creatures are on the battlefield, sacrifice Withering Wisps.
: Withering Wisps deals 1 damage to each creature and each player. Activate this ability no more times each turn than the number of snow Swamps you control.
- [ICE] Ice Age #168 (U)
- [ME2] Masters Edition II #114 (U)