[Rendar]

Elven Knight used Sacred Prism.
Spatial Terror takes 123 Light magical damage. (Sacred Prism / Jade Insect Whistle)
Spatial Terror takes 94 Light magical damage. (Sacred Prism / Jade Insect Whistle)
Elven Knight used Sacred Prism.
Spatial Terror takes 94 Light magical damage. (Sacred Prism / Jade Insect Whistle)
Spatial Terror takes 94 Light magical damage. (Sacred Prism / Jade Insect Whistle)


Twould seem that Sacred Prism does not interact with Cast Order as it should, instead it gives the bonus (+37 here) to the initial target hit by the cast, and then the bonus is not applied to other targets hit.

[Rendar]

Seems to be happening with multiple AoEs, actually. Lantern Bearer auras are another one affected.

[Neus]

This should be corrected in 2.81.