Runes appear as small, greenish gray, N-shaped objects embedded in large blue rocks. The rocks are dark blue on the inside and electric blue on their outer rims. They have many cracks running through them, dividing them into smaller rocks which don't have runes.
Runes will, on contact, kill any Viking. Rats are immune to runes, as are any frozen Vikings (due to their layer of ice protection) and the Viking icebreaker in the drakkar. Other than its powers of instant death, it behaves much like a normal rock. It can be hard to avoid the runes in some levels, as it is always placed where the Vikings have to venture, in order to increase level difficulty.