Arctic Fleetfoot

Cumulative upkeep {1} (At the beginning of your
upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Arctic Fleetfoot can't be blocked unless defending player pays {2} for each age counter on it.
Whenever you pay Arctic Fleetfoot's cumulative upkeep, it gets +1/+0 until your next turn for
each {s} spent to pay it.