Some of the runes in this set might be preferable to activate during or after combat, so the fact that this cannot attack unless you (potentially) waste a combat trick or post-combat ability isn't ideal.

Maybe this should not be able to attack unless you control one or more Runes? I don't know how heavily supported this archetype is (seems pretty huge in this set), but if it's a lot of support, you might want to consider requiring at least 2+ runes...

I got this advice from the new Gadrak, the Crown-Scourge card. It would make sense here to use something more like this, though 4 would almost definitely be too high.

A valid critcism. Runes There are a number of cards that can produce runes multiple times, so two is probably the safest. This will really force this card to only be played in rune-heavy decks in limited, but I believe there's enough cards that make rune in this set for that to be possible.