Deckbuilding with Companions

This is an aggregated post for builds with the ten companions from Ikoria. The builds can be constructed Standard, constructed Modern, and also Commander.

Commander Builds:

Eutropia with Keruga Companion Casual Commander Build
http://mtgadventures.blogspot.com/2020/06/eutropia-with-keruga-companion-casual.html

Lazav Mastermind with Gyruda Companion Casual Commander Build
http://mtgadventures.blogspot.com/2020/06/lazav-mastermind-with-gyruda-companion.html