ways to get a minion type thing

[Lady-J]

looking for ways to get a minion type dude that will scale with the characters level, the character would be an anti paladin looking for a way to get the level 5 class feature to grant an undead as opposed to an outsider, also looking to make it be a dragon(so an undead dragon) so i'm going to need some way to get a animal companion as well as that feat that lets you use magical beasts as animal companions(cant remember the name of it atm) so it could be used as a mount

[Starbuck_II]

animal ally grants an animal companion at character level -3. But limitde list.

[Lady-J]

figured out what the one for magical beasts is called monstrous companion will talk to dm about letting it be a dragon