Do you think that Circle of Power is a reasonable set of effects for a 5th level spell? I think that's a good comparison point for balance, here. Both spells make it harder to affect creatures inside with magic; and both have a damage resistance component.
Circle of Power has the following advantages:
- It's a bigger area
- It gives better damage reduction to creatures inside, which doesn't use a reaction
- It's mobile
This spell has the following advantages:
- Lower level
- An AC bonus
- Temp HP, which refresh whenever anybody takes elemental or force damage
- The resistance feature applies to all damage of the designated types, not just from spells that involve saves
- A significantly greater disincentive to target creatures inside with spells; blindness and subject to a future incapacitated effect is definitely worse than just giving advantage on saves. Even the blindness on its own is worse.
I think if you made it 5th level, removed the "use an action to incapacitate" bit, and made the temp HP one time only, you'd have a spell that was roughly comparable to the other (quite good, in most people's opinion) 5th level circle of protection vs magic.