In the UK Moria/Goblin Town tend to have wraiths thrown in on top with the shamans...pretty filthy stuff.
She's not completely useless against Isengard. She can Fortify your heroes to protect against Saruman (or your troops to resist Sorcerous Blast! ha) and gets Blinding Light without having to expend Might, which with Grima around is no bad thing! She's definitely good. My reason for not using her isn't a debate over which spells are most effective but simply that I usually need her to lead troops.
The reason for the Twins was that for the tournament the top 2 models have to equal or exceed 250 points, so I was thinking Galadriel/Twins with 9 Might is a pretty good choice and will also save Leggy's Might.
I may however just move away from Arnor completely, dropping the Twins and take Thranduil King of the Woodland Realm with Mirkwood elves. Keep the 12 bow shots and with Thranduil some serious hitting power