Debug appears to only work on players, but there can be damage sources in some mod(pack)s that need to give IFrames but only affect mobs, not the player, and even at least one unmodded case.

Examples of other entities needing IFrames from a specific damage source, not globally:

• Consecration's holy water and blessed powder, both dealing damage to undead, while holy water also gives Regen to non-undead.
• Blazes being thrown into water.

Hello, sorry for the late reply.

I'll consider this. Adding mob-by-mob and source-by-source checks may end up being very expensive in terms of computing resources, so I'll have to play around with different implementations to see how viable this may be. No promises for now.