Add (untradable) nodestone rewards to the Exploration rewards for arcane river collection, which would have a decent obtain rate identical to that of Occult Cubes. I would prefer that Nodes replace Occult Cubes as a reward for arcane river collections while exploring with a chance to obtain 1x, 2x-3x, and 5x untradable nodestones depending on the difficulty and level needed to collect the monsters in the set, as well as the time to finish the exploration. You could obtain nodes on characters that haven't achieved 5th job yet as long as one of your characters has 5th job (obviously to be able to go to arcane river and collect the monsters in the first place).