The border has a couple of different measurements around the card, so buckle up
6/5 Illustrated by Yoshitaka Amano Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Legal Modern Not Legal Brawl Legal Legacy Legal Comp
You cannot decide to change how many creatures youre tapping to pay the convoke cost while youre casting the card
Omnath, Locus of Creation fits especially well in Yorion and/or Risen Reef decks of which there are a few in the current metagame, and since these decks also play pitch-elementals (Solitude, Fury etc.) drawing multiple copies of a legendary card like Omnath, Locus of Creation also ends up serving other purposes
I think its one of the most powerful combos in Magic, and thats why I discuss why you should play Izzet, who you should pick as your commander, and offer a sample decklist to inspire your deckbuilding
Three is a heavy cost making it rarely viable to do early and the effect is not typically something you want to cycle away late