I do think it's possible to work around the usual issues people think of when it comes to BST; make Charm something that you apply to a mob and then which has a chance to proc when that mob dies. You'd start out in a dungeon without a pet and have to rely on your own attacks, then you pick something to charm and hope for the best. Really basic mobs like the first pull could be 100% chances. Enemies with stronger abilities would have a lower success chance. You'd have to release your current pet to attempt another, which becomes a gamble against being stuck with only your 123 again if the new charm fails. Somewhere around 40-60 you'd get the jug pet ability, which gets you a pet without the need to charm but it can't do anything special at all. Pet commands would simply be 1-single target mode, 2-AoE mode, 3-CD to have pet use a special if it has one. And finally, make the charmed state last around five minutes so that multiple charms need to be used per dungeon.