taybul

Burn follows the same rules as dots when it comes to Nether protection: it can proc off initial application, but not off any of the ticks.

Proof from recent Brut kill:

20:06'02.187 Malocadi's Shadow Bolt hits Brutallus for 4835 Shadow damage
20:06'02.765 Malocadi gains 7 from Aura of the Crusader
20:06'02.812 Malocadi's Soul Leech heals Malocadi for 609
20:06'03.187 Malocadi gains Nether Protection
20:06'03.187 Malocadi is afflicted by Burn

Few more things:

Felmyst: During air phase, when she's about to start her breaths, put up a CoD, threat-permitting. Should go off before she lands.

Twins: Nether prot can proc off conflag which is nice if your pvp trinket is down.