Overflow Dragon (DANE-EN004) [Dark Neostorm]

When a monster(s) on the field is destroyed by card effect (except during the Damage Step): You can Special Summon this card from your hand, then, if 2 or more monsters on the field were destroyed by that card effect, you can Special Summon 1 "Overflow Token" (Dragon/DARK/Level 1/ATK 0/DEF 0). You can only use this effect of "Overflow Dragon" once per turn.