Treant's Creeping Crud dot blocks regenerate buff. Bug?

[Nibblewitz]

Probably not a bug. The numbers next to the spell effects mean something. Spells with similar effects that correspond to the same effect number won’t stack.

For example, Focus of Spirit and Shield of the Magi don’t stack because their increase Heath effects are both effect number 1.

Iirc, you are not able to regenerate yourself when you have the boiling blood dot on you. Because they he decrease hit point per tick and increase hit point per tick have the same effect number.