First of all, High Elves draw their spells first. When you need either a High Magic or colour spell you can guarentee that you get it. As a High Elf Lord, you really must know all your choises. In the beginning of the magic phase, plan carefully what you want to do, and then decide whatever you will change any power cards or not. On many desperate ocassions I have traded ALL my power cards and recieved Total Power in exchange.
Runes are simply too useful.
As an Elven lord I never neglect a chance to filed a runesmith with three Runes of Spellbreaking. This gives my mages a chance to lay their hands on something far more useful than those boring old dispel scrolls. Wand of Jet and Book of Ashur as my principle magic items. It can really slow down elf infantry regiments. I prefer Spell familiars over others, since the effect is very straithforward.