Prime Speaker Zegana

Janosik

Prime Speaker Zegana calculates +X/+X as the total power of other creatures you control, not, as written, the total power of all creatures you control... it does not include it's own power.

This is not particularly noticeable if you don't already have a Zegana in play (since it enters as a 1/1 before getting +X+X), but is very noticeable you reinforce a larger Zegana that's already in play.