Runetracer concentration mechanic question:
So can they have multiple such effects running as long as they make the check?

First impression to concentration checks every round is thatís too many dice rolls, if they can keep multiple effects going that way, itís wayyy too many rolls.

You could make the DC for Spells with Durations higher, Concetration is just a +2 while 1 hour and more could be +5 and so on.

Good luck whatever you choose!