Arixmethes, Ancient ground

Arixmethes, Ancient ground gets +1/+1 for each
age counter among permanents you control.
Whenever you pay the cumulative upkeep cost
for a permanent you control, you may pay it as if
the number of age counters on that permanent
were equal to the number of age counters on the permanent you control with the fewest age
counters on it, but not zero.