Guild Wars 2

The patch notes imply this was addressed, but in the current fight in a Blackgate overflow, it healed from 50% to about 90%, causing a loss.

2 things, its not a blackgate overflow its just an overflow, and its not a bug the heal, its the twisted menders that get close, they can heal a substantial amount, just have someone on the lookout for them.

ok I just watched this happen, blue was at 75% red was killed, the moment red people turned up the event upscaled and gave the bar a nice boost, when they left and it downscaled the health bar dropped considerably.

so its 2 possibles, 1 heal from mender, 2 upscaling of event.

hope this helps you arranging further runs.