[Executor]

Yes Iron Blizzard is an amassing spell and yes arrow fend tends to stop it. But even with arrow fend you still do a fair amount of damage since you cast over 30 projectiles. The shear number of projectiles you can put out is enough to overpower arrow fend sometimes.
I may be getting off topic here but arrow fend doesn't stop Ulm. It more or less equals things out for the other nation. For example those 5 Bows of War Ulm paid 5 gems for effectively become a single Bow of War under arrow fend.

I should state that there are also only a handful of nations that have A3 mages to recruit. Of course there are twice that many much which have A2 mages but you'd still need air boosters or communions or crystal shields and stuff to protect your armies and all those tend to cast. I should also mention that a single turn that some nation takes to put up arrow fend is enough for iron blizzard to annihilate an army and than switch to other stuff such as magma eruption as Shardphoenix stated.

I agree that Destruction + Blade Wind doesn't work as well in practice as it sounds. Here are the five spells I found most potent for Ulm.
-Iron Blizzard
-Magma Eruption
-Strength of Giants
-Weapons of Sharpness
-Legions of Steel/Iron Blessing

The first two basically crush most types of troops. And the 3 boosting spells turn your flail infantry into killing machines. I've seen Grendelkins, Treants, Zmeys and all sort of things chopped under Ulms boosted flail infantry.

I'd say that Ulm is currently the strongest MA nation IMO. Before they were crappy but now they got just too many small boost which combined are a bit OP.

I may not agree on a number of things in CBM 1.9 but so far I've experienced first hand only two things that really need to be removed. Agarthas darkness PD and Ulm Forge.