Urtet by paying ({W} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) and tapping it, putting six +1/+1 counters on each creature you control, as they are all Myrs due to
Maskwood Nexus.
Activate
Crystalline Crawler's first ability six times by removing six +1/+1 counters from it, adding ({W} magic symbol) ({U} magic symbol) ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) .
Activate
Pemmin's Aura's first ability by paying ({U} magic symbol) , untapping
Urtet.
Repeat.
Results
Infinite +1/+1 counters on creatures you control except