I put s lot of summons in for Aeron. I really wanted him.
But I would finish leveling BT first. He is super useful in Titan, AW and many other places.
I love Areon because he is a purple healer and gives me more options from my hero pool. I see BT as radically different. Are is almost 100% defensive, while BT’s attack buff makes him a bunch offensive. At least that is how I use BT and how I think I will use Areon.