mellored
Legend
It's more that the mechanics don't mix well.If I had to guess, I think the big reason they made the Rune Scribe so light on internal mechanics is that it's like a weird compound of Wizard and Warlock--since it essentially gains the equivalent of a package of invocations from each Rune it acquires. I really do think they should've given it a meatier capstone though. Assuming you can find even one more Major Rune you haven't learned, you may never benefit from the 5th level stuff at all.
i.e.
Reroll fire damage, then give you air and cold spells.
Or inscribing fire onto a blade, then cold overwrites it.
Inscribe a rune that makes you and creatures around you immobile, then flying.
Or freezing a lake to cross it, then getting waterbreathing to swim though it.
Hmm.. actually freezing water and water breathing could be a powerful combo in certain campaigns. But still, most features are competitive too much with each other, not complimentary.