A Glistening Armor Dyad is a necessity. Reapers consume mana very rapidly especially during Shadow Reaping. Even with Glistening Dyad, you still need to carry around Mana Potions. You also do not want to rely on your Shadow Lash to replenish your mana. The sole purpose of Shadow Lash is to be used as a cooldown buffer for higher priority skills. The ideal Glistening Dyad to have is Glistening Hardy Dyad.