The most evil combo vs. a single enemy (or possibly a group if you can catch them in the spell radius, though you can only ensure a kill on a single one) is at a higher level, usually nicknamed the microwave oven: Sickening Radiance (plus maybe a Silvery Barbs for good measure) in the ring to be cast by the Familiar, Wall of Force or Forcecage from the caster, prep Counterspell in case the fucker wants to teleport out of the area, then sit back and cast Silvery Barbs whenever the target makes the CON save until it reaches 3 levels of exhaustion. (Then it will have disadvantage. You can still SB them if you wish.)

So yes, the Spell Storing ring can still be a problem.

(Giving it to the melee martial character loaded with Steel Wind Strike is also fun. Monks are possibly the best for it, they can rush into the middle of the enemy group with Step of the Wind and still cast the spell. Then end the turn next to the enemy wizard.)