Cumulative upkeep {1} At the beginning of your end step, Magmatic Core deals X damage divided as you choose among any number of target creatures, where X is the number of age counters on it.
2006-07-15
Each target must be assigned at least 1 damage.
2006-07-15
If Magmatic Core has no age counters on it, the only number of targets the ability can have is zero.
2006-07-15
The damage is divided when Magmatic Core's ability triggers. Increasing or decreasing the number of age counters on Magmatic Core after the ability triggers but before it resolves has no effect on the amount of damage that's dealt.
2019-07-12
You can choose zero targets. In this case, Magmatic Core deals no damage.