Either a super tight delay with very little feedback, and/or reverb with a small density and diffusion time. It's like you can almost hear every grain of reverb on the voice, rather than it being a lush full sound. Also maybe a little bit crushing, chorus in there too.
I'd hesitate to saying he's using a lot sending and automating what goes where and when. You can hear it when the effect kicks in, the tail of it goes to a bigger reverb. So maybe evening some ducking going on in there as well.
Possibly even eqing the busses to extenuate specific parts of the words so they're more effected etc
Either that or he's just choppin up the vocals and doing it manually, or using something effectrix.