Ah, the new Agony replacement skill. I have not been on the PTS, so pardon me if this has already been said.

I could not tell whether this skill would be any good for solo play from the patch notes. A lot depended on the strength of the heal. Thankfully it is quite strong, almost twice as strong as Refreshing Path, which itself is stronger than Rapid Regen or what you typically get out of Siphoning Attacks. This is why it might find itself into your build.

It works quite well in duelling. I look at it as a way to mitigate burst. In many cases burst is achieved by stacking delayed attacks that explode together. While, say, the opposing warden or sorc is busy working on that, you can choose to (shield and) take some damage early with Malevolent Offering. When the burst arrives 2 or 3 seconds later you have typically already healed back up to full and now have a strong heal going to get you through the burst.

Where it falls down is when you are outnumbered. If you are under severe pressure, especially with some templar already spamming J-Beam on you, Malevolent Offering is a bad move. I am undecided whether to keep the skill in the long run, because of it's inability to perform in those situations. It is not a replacement for Healing Ward, and you may thus strain for bar space to fit both. This is the biggest drawback, if you compare it to Living Trellis. I find that with Trellis + Harness/Dampen, I can choose to drop the resto staff / Healing Ward on warden. I don't think Malevolent offering will allow that. In fact, it could work in conjunction with Healing Ward, in a pererse sort of way, since you can use it to make the ward bigger. Thus far, however, my choice has been to shield first.