Age counter

Age counters are usually placed during the upkeep step. They are exclusively used by cards with cumulative upkeep. 
In Coldsnap, age counters were not only used to keep track of the costs attached to cumulative upkeep, but also to track effects based on the number of age counters on that permanent.
==Trivia==
* In Magic Online, the counter is colored green as its considered a positive effect and shares its icon with Delay, Depletion, Eon, Fade, Hour, Hourglass, Isolation, and Time counters.
==References==