It's already got a 4+ ward save, protecting it from Bolt Throwers and the like never hurts. I'm also partial to a Nurgley warshrine because converting it from a Corpse Cart is so easy
If you're going mono god, I'd have to pick Slaanesh. Its benefits are outstanding, ITP with the ability to flee, and the cost is crazy low so you can fit in more units. You can always use the Blasted Standard against those Flamers (3+ armor and 5+ ward should be fine I'd think
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