[Miscreant]

In tactics, most doors which can be abused will become magically stuck open. The deva, for me, was the absolute smallest detail. Don't you have a character with a sling? Magic missile? Innate larlochs minor drain? Any of that will interrupt (usually) the long casting time of the spell.

Now see if you can do it with only the stock NPCs at your side, with only the PC being customized.