Misc. D&D question (arcane spell combo)

Hey guys, so the spell combo I'm thinking of is:

Round 1: Entangle (or Web) (1st lv)
Round 2: Cloudkill (5th lv)
Round 3: Otiluke's Resilient Sphere (4th lv)

This would have to be attempted by at minimum a 9th-level wizard (who can cast 5th level Evocation spells). Seems pretty potent, right? You trap the enemy, sent a cloudkill his way, then trap him inside it...

Another thought (if the enemy was too big for the Otiluke's resilient sphere to contain) was Rd1 Entangle or Web, Rd2 wall of force to somewhat barricade the target against a wall (esp. if fighting in a cave and you can sort of corner it), Rd3 cloudkill over the wall of force so that it lingers around in that area, affecting the enemy.

At first I thought entangle or web would not be necessary but I think it'd be important to to try and restrain creatures that can fly, or would otherwise just move out of the way of the cloudkill.


Is this feasible/viable by the rules? Especially about wall of force, it says breath weapons and spells can't pass through it, but that sounds to me like you can still cast a spell on the other side of it, right? (i.e. a fireball won't penetrate through the wall of force so could you just cast the fireball on the other side of the wall?)

I would agree that you should be able to cast the spell on the other side of the wall. Entangle-ing and then Wall-ing someone would be pretty effective for keeping them in place. Entangle does allow a save every turn to get free, but if they are also walled they're basically screwed. Dumping any offensive spell in on top of them would be pretty brutal at that point. Is the casting time instantaneous on all of those spells? Regardless, it would still take 3 actions and cost you three spell slots... so it would have to be a pretty intense enemy. I suppose if you're a level 9 caster you should have enough other spells available, but probably not that many more of the 4th/5th level variety.