It needs to be at most one legendary rune. Honestly, one of each of the three runes would be far more in line given we lack repeatable ways to get the spark without farming boring bosses ad nauseum. I have one, just one Ohm and I need that for runewords once (if?) I ever find or get lucky and craft a Tam. The current runecrafting system is a clusterfudge and is super draining. It’s the exact opposite of an endorphine hit.