The idea here is that they cast runes without a casting time, so they can keep moving. Like Melia in Xenoblade chronicles, the runes themselves don't do any dps, specifically. They cast them in the air and they stay active, granting the party a small buff of sorts (small HP regen if we want that, damage buff, attack speed buff, etc). Nothing huge since theirs no timed expiration, but varied buffs depending on the rune. Maybe certain runes enhance the previous rune to make it stronger or open the AoE, or multiple runes out create different buffs.The rune caster can only have three active runes running at once. Possibly there's a sll cooldown between casting runes.