Magma bolt and blade wind are going to probably be your best bets for your smiths. General evocation spells.
Ideally you'll pull an F2 smith random or a pretender with fire magic so you can cast flaming arrows (on indies, not your arbalests). Research this over evo if you can pull it off. You'll need conj 3 for power summoning regardless.
Dropping a few Curse of stones will help as well in a big battle, but it won't help much til your troops start getting trampled to death, and you want to keep them away with ranged attacks if at all possible.
It's not a pretty matchup for Ulm though. Good luck.
F2 smith won't work in 3.08 since Fire Arrows has been raised to F4. You'll need to forge a skull of fire or a flame helmet with your pretender or an F1D1 shaman.
-Max
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Bauchelain - "Qwik Ben iz uzin wallhax! HAX!"
Quick Ben - "lol pwned"
["Memories of Ice", by Steven Erikson. Retranslated into l33t.]
Yes it will Max. Phoenix Power to F3 and then an extra gem to bump your level to 4 since it only takes 1 to cast. I referenced needing conjuration 3 in my post. (You need it for blade wind even if you go the evocation route, which is a large upgrade over magma bolts)