Unknown effect damaging my units

[Zero]

What is this effect?
https://i.imgur.com/uuDeouR.png
It is damaging my units, has no name and is unknown to me when it applies.

[mk31bolo]

Looking through the game's encyclopedia, that symbol matches the "Power of Deep Ocean" skill of the Kraken. The effect is the same (your image shows more damage, but that would be the result of the Kraken being higher than level 0). It's inflicted automatically on all opposing units in range at the end of it's turn. Have you been fighting one?

[Zero]

No I haven't, I haven't even entered the ocean, but it might be right, since I experience this effect only on maps with water castles and creatures. It would seem that this effect passively stretch out in stupidly long range.

[mk31bolo]

Well, the power states it affects all enemies within three spaces, so it sounds like a bug. And a pretty nasty one at that. :(