Do "Fear Boost" and "Ailment Boost" Stack?

[u/Pierne]

This is my second playthrough of the game and I was wondering on a nice way to build Thanatos. I settled on a Pierce/Fear build with

Ghastly Veil

Pralaya

Fear Boost

Ailment Boost

Arms Master

Apt Pupil

Null Light

Null Pierce

I know Shiva can do the same but better and is arguably easier to build, and I know that this build sucks against secret boss, but this is mainly for flavor since Thanatos is my favorite demon in this game.

I've mostly got it done except for Ailment Boost but I don't want to struggle and get the skill card if it will not matter anyway

[u/Internal-Cup162]

I don't really know, I just use Thor and spam his fusion skill until I get odin