Because Mowu's replacement effect affects only Mowu, it will apply if Mowu somehow enters the battlefield with one or more +1/+1 counters on it and give Mowu an additional +1/+1 counter
Well, how about a character that looks like theyre wearing an outfit that belongs on an woodland/jungle elf, and a dipped beak on their hood
Its commander is Hazel of the Rootbloom, who can tap tokens for mana, as well as doubling up any tokens
It might have taken three years for Zilortha, Strength Incarnate to be printed in-universe, but the precedent was nonetheless set
With stations, waterbending, convoke and good old mana dorks (among many other options for tapping your permanents) you overwhelm opponents with creatures, just remember a few anthems
How broken could it possibly be