iMACobra
Experienced Necromancer
Did you anchor Lokil? I think if you anchor him and respawns, he'll actually level up more with you if you leveled up yourself. Bandit Chiefs will eventually respawn if you leave them unattended for a long time. Adam has experience with respawning thralls. Illia levels up with you all the way to 40, the Dead Thrall level cap. She eventually learns Frost Cloak and Icy Storm. If you want Blades Armor on her as a thrall, make her join the Blades and then thrall her. She's also a good sacrifice for Boethiah (w/ Blades Armor on) because of her follower bug.