First, ask your opponent about the 'High Elf High Magic Lore Attribute'... his 'HEHMLA.'
HEHMLAAAAA!!!!!!

(sulks)
HEHMLA...
Anyway, I know that a lot of High Elves players love to stick their caster in a block of White Lions, and then march up the field totally unharmed as they cast piddly spells in order to take on an absurd Ward Save for their block. Let's not even talk about the Everqueen, either. -_-
I don't know whether the issue has been resolved, but whether Drain Magic affects their Lore Attribute is debatable. Best to ask your opponent. I, personally, think that it does.
Regardless, I like Focus of Mystery & Becalming Cogitation against HE High Magic, since outright dispelling equates to dispelling their ward saves. If you want to go crazy, bring two caddies (dispel scroll & cube of darkness).
Apotheosis to negate Terror/reduce their WS... HoG for obvious reasons... Aracne Unforging for BotWD...
If you're taking High Magic, then don't forget about Razordons! They are one of our few units that ably benefit from every aspect of Hand of Glory.
Take a block of 5 or 6, since you shouldn't need but one Salamander to soften up those blocks.
The Bastiladon is great against HE... just don't use its Solar Engine against PG and such. Rolling a 4+ on its table and even average 2d6 hits will put a big hurt on pretty much anything HE. This thing could pluck a few wounds off a Frostheart before it gets into combat - S5 wounds deny its armor outright, if I remember right.
Here's a mini-tactica for dealing with those: http://www.lustria-online.com/viewtopic.php?f=15&t=15131&start=10
I like Skrox w/ poisoned Skinks against them as a main force, backed up by Skirmishers. They won't care so much about -1 S since their attacks are poisoned, and they're immune to Terror thanks to the Krox.
More stuff, but I'm off to work now! Take care.