OK, here's the crack. Completed all the realms and defeated all the bosses including Skorne in the Desecrated Temple and am ready to embark into the Battlegrounds... but I missed a runestone somewhere...
Is there an easy way to tell which one? Its the middle blue one on the circle of runestones in the Tower (if that helps) and I'd like to try and avoid playing through every runestone level again
Any help is truly truly appreciated

Go talk to the summoner, he will tell where is the runestone, go in that level you should have a meter showing if you're close or far.

I played the game recently, it's in the sky dominion in cloud docks, it's behind a wall you have to destroy(behind the meal)

Go talk to the summoner, he will tell where is the runestone, go in that level you should have a meter showing if you're close or far.

how do you get him to tell me where it is?