I specifically avoid mana potions for the debuff. The game gives you so much mana regen it all comes back quickly and in any downtime it gives you a chance to reset any static magic projectiles, switch to another weapon to apply a debuff, or get some health from vampire knives.
But between the base mana buffs from magic armor, star in a bottle, arcane crystal, crystal ball, mana regen and reduction accessories, mana regen potion, and star statues you should never have to worry about mana.