Herald of Thunder damage affected by spell suppression

Seems like this is the case, quite noticeable when activating Eater of Worlds altars that grant spell suppression. I would assume it shouldn't have an effect since Herald of Thunder is not affected by modifiers to spell damage. This is harder to determine on Herald of Ice but it might be affected as well.

It is a little wonky because herald of thunder is secondary damage so it doesnt benefit from increases to spell damage.

However it is still spell damage so spell suppression properly works against it.

Damage can't be both secondary and spell damage. HoT deals secondary damage.

Spell supression though mitigates secondary damage as well as spell damage. Two conditions must be met for this:
1. The damage comes from a spell;
2. The damage is not self-inflicted.

This also applies to spell block and spell dodge.

Spell Suppression clearly says "chance to Suppress Spell Damage" so either it shouldn't apply or needs to be reworded.