I’m now a Sadhu main, although my build differs from the meta PD2 sadhu builds, here are my thoughts on the class. My main build is C2>Diev1>Sadhu3>Miko>Taoist.
C2 Bokor1 Sadhu3 PD2 is more of a dps centric, soloist build. The priest variant will be better if you want good support for party play too.
Just like what @siderit99 said, the SadhuPD2 build is built in a way to get maximum damage out of PD’s Vapor-Incinerate. The build screams more of PD rather than Sadhu. Sadhu is just a damage buffer in the build, which is why you feel that the class offers nothing more than just damage buffs.
For PD2s, there isn’t really much rotation needed for sadhu to shine though. At high transcend levels + enchancements, just Vapor, Hex + a full screen Pandemic will often do the job, add in a couple of effigies if they didn’t die.
Which is why I build my main as Diev1 Miko Taoist instead, it capitalise on what Sadhu is capable of and makes the build feel like it is Sadhu. :3
So on to the skills and what is brings to the party.
Transmit Prana transmits 60% of our stats to another party member. Currently there is a bug in which we can cast it on ourselves and get an extra 60% of our own stats. Unlike priest’s blessing which target party wide, sadhu’s TP only can target 1 player.
As the balance patch kicks in, skills that previously will lock monsters in place such as hamaya, frost cloud, fire pillar, retreat shot etc (due to position desync) no longer ‘soft cc’ the mobs. This is where Sadhu’s possession comes in. Possession is an aoe which roots monsters in place. This helps quite a bit in party play where the party wants the monsters to stay at 1 location while the other dpsers do their job.