[Shardphoenix]

Summon Lammashtas takes only one battle turn and a death gem to use

In my experience, they usually kill a necromancer first.

H6 Banishment

16 communion slaves? That`s a really big communion.

Iron Blizzard spam

Tower shields.

permanently, too with a minor earth bless

If you`re communioned already - why not add "summon earthpower"?

I'm personally more worried about Rl'yeh

Of course you are - after all, Marignon is a closest thing to a silver bullet against Ermor - H3 High Inquisitors, Harbringers, Holy Pyre...