My personal worst of fives:

1.) Bleed fire. It´s more of a detriment then help, I´ve yet to find any use for it.

2.) Breating bubbles: Yeah, nice, but .. well, no. Thanks to the armor system i rather buff or restore magic armor instead.

3.) Sabotage: Sounds cool as a concept, but how am I supposed to know if my target even has grenades? I rather use the AP and the memory slot to do something usefull, like pure damage or apply a usefull CC.

4.) Smoke cover: Highly and I mean highly situational. The 2 AP cost got this skill a spot in the list.

5.) Provoke: If the taunt mechanics where any different (like forcing the target to do basic attacks for instance), but as of yet, I don´t see a difference beneficail to me in AI behavior after a taunt.

By the way, Blood Rain is actually a pretty decent spell. The surface created by it can be used in many different ways. Elemental affinity as a necro, max heal nuke for blood sucker and tons af damage for grasp of the starved.