Beast - transformation with Rune Maw??

Hey guys.
I'm looking into different builds for my spellcasters and I'm looking into beasts. I'm seemed dragged to the idea of a butcher or slaughtermaster but for a little trick.
My question is.
Have any of you guys used a combo for transformation of kadon with the Rune Maw??

I was thinking of going big and because the spell says, the model joins the unit. So with the Rune Maw it can't be dispelled?? Could work well. I was thinking of trying a butcher but lv2 is making it hard to even get the spell.

Sadly, that isn't going to work (nice though it would be).

The Rune Maw prevents spells from targeting the unit.  It does not prevent spells from being dispelled.

The dispel attempt is not a spell, so it is unaffected by the Rune Maw.

Well..... It was worth a thought. Would have be good.