Phantasmal Web is a potential encounter-ender all by itself at 5th.
Other than that, the absolute essentials (Black Tentacles, I'm looking at you, just for example) seem to be listed, and I'm not going through that list in detail.
I dont consider Black Tentacles anything like essential. It scales very poorly, is only really useful against full arcane casters who MUST have an answer to grappling (or they would have already died) and gets in the way of the rest of your party. Something like Blindness is much more effective for shutting down annoying Wizards.
Personally I consider the various no SR conjurations essential. They let you target any defence and have a major impact on the battle. Early on stuff like Grease, Glitterdust, Create Pit and Stinking Cloud can be encounter ending almost on their own. In the mid levels adding persistent to them keeps them highly relevant. They lose out a bit at high levels, with the exception of glitterdust, but at that point you are getting Dazing no SR conjuration damage spells.