Feat: Mammoth Lord Dedication
You've undertaken the ultimate challenge of the Mammoth Lords and tamed a megafauna. You gain a megafauna you tamed as a young animal companion. Your megafauna animal companion must be a megafauna appropriate to the Realm of the Mammoth Lords;. While an animal companion usually starts as Small, you can begin with a Medium version of that animal (changing no statistics other than its size).
Contrary to the usual rules for animal companions, this feat can give you a second animal companion. If you have more than one animal companion, you can adventure with only one of them at a time. You can switch between them like a beastmaster does. You gain the Call Companion action, as the beastmaster archetype, and you follow all the other rules found in the Call Companion sidebar; see Beastmaster Dedication for details on this action and the rules for multiple companions.