Channelling
A foe is holding an ability open, pouring a healing beam into a wounded ally. They do nothing else while they channel, and the beam keeps flowing until you cut them down.
In detail
Frost Warden: a 2-second windup, then a 50 HP per second heal beam to the most-wounded ally that is not a minion, the boss ahead of anyone else. A channelling enemy skips its strike timer entirely. Lock onto it by tapping its sprite to focus your damage and break the beam.
More in glossary
From the current development build. Content and balance may change before release. This public reference includes discoveries and does not reflect your personal unlocks.