At the same time, how would you execute the combinations to any notable effect? Titan decks spend the entire game to do the same, and they win the game in an instant once they are done.
Ok, we can use shorter rune words (totally fictional or real Norse short words) — with 2, 3, 4 letters.
The entire deck or large portions of them would have to be made of runes to counteract the issue, and the defeat of an army with a lots and lots of magic scribbles is... a little weird, given the context and the scale of what you try to accomplish.
Arcomage is competition of mages, isn't it? One of two mages searches, collects and uses runes for power and victory. Look at rune word as at single powerful spell card divided to several ones.