MTGNexus

Ok, so mutate doesn't trigger ETB effects but what if I mutate Vadrok, Apex of Thunder as my commander using Opal Palace's ability that normally adds counters? I assume I don't get the counters because it makes more sense if it doesn't ETB that it also wouldn't get this but I figure I need to ask.

You're correct, no counters are placed on anything in this instance. "Enters the battlefield with N counters" is a replacement effect, and if the event it replaces never happens, the effect never applies.