Flalrmir, King of Many

{1}{g}: Create a 1/1 green Frog creature token
with a croak counter.
{g}{u}: As an additional cost, pay X, where X is
the number of Frogs you control. Place a croak counter on each Frog you control.
Frogs you control with a croak counter on them
gain reach, then gain haste, +1/+1 for each croak
counter, vigilance, and trample for each
consecutive croak counter.