Do NOT need those “Mastery Reset” items anymore.If you still have some, it will use them, but they are just leftover relics that are no longer needed.Nodes that were previously unlocked from Cores will stay unlocked.But all the smaller incremental Units/Gold for leveling up within each node are still required every time you reset Masteries.
Yes, existing “unlocked” nodes remain unlocked after reset.Those from using Stoney/Carbo/Class Cores, as well as the BIG Unit ones (cruelty/precision).But all the small amounts of Units will be needed again for each of the levels within nodes (like maybe 30-50 units overall depending what you use)