There were two skills nerfed severely in Patch 0.7.2b;
Both of these skills were released with trees in a state they should never have been released in - and on behalf of the team I apologize that such drastic changes were subsequently needed. Transplant is now in a more reasonable state, however we recognize that Reaper Form is now needing quite a lot of love - we have been discussing both how best to bring Reaper Form's tree up to a higher power level, as well as how to improve our internal QA processes to avoid repeats of Patch 0.7.2b.
Transplant
Transplant is an Acolyte skill with a 4 second cooldown that had a node which, for the investment of three points on its tree, would give your character a flat 30% reduced damage taken modifier. This lasted for three seconds by default, with an adjacent node increasing the duration of this buff by 1 second per point invested (maximum of 5). There was also an adjacent node which, for each point invested, would make this damage reduction 10% more effective (maximum of 40%).
Transplant is a damage-dealing teleport skill, and it also offering the above damage mitigation in return for so little investment simply isn't acceptable. We would feel differently if it was the product of someone availing of synergies between a specialization tree and unique items or an item set, but it offering so much in return for so little made it feel mandatory for all Acolyte builds.
Reaper Form
There were multiple issues identified with the specialization tree for Reaper Form. One example being a node which increased Reap's damage by 10% per point (maximum of 3), for each percentage of your maximum life that you are missing when the skill is used. That is an investment of three points potentially granting 2,970% increased damage.
It's an ARPG, and as we expand both the challenges and the rewards for characters at the endgame, we need there to be something left to offer. A handful of points spent on a single tree halving the damage you take or granting multiple thousand percent increased damage leaves too little for other specialization tree nodes, class passives, unique items, legendary items, Lost Memories, and other systems to be compelling. We want your characters to feel powerful. We don't want them to be immortal a few hours after creation.
Edit: Typo