Tiered with 387 mods works perfectly fine on my modpack. Tiered with 388 mods crashes when damaging an entity. Disabling a mod to get back down to 387 mods prevents the crash.
In the logs below, I used an insignificant mod on my modpack which is Chalk - But I have tried dozens of other mods and the issue is consistent: No crashes at 387 or lower, crashes at 388 or more.
Tiered with 387 mods works perfectly fine on my modpack. Tiered with 388 mods crashes when damaging an entity. Disabling a mod to get back down to 387 mods prevents the crash. In the logs below, I used an insignificant mod on my modpack which is Chalk - But I have tried dozens of other mods and the issue is consistent: No crashes at 387 or lower, crashes at 388 or more.
Crash - Tiered with 388 Mods
latest.logs with no crashes below if it helps. 388 Mods Without Tiered -latest.log Tiered with 387 Mods - latest.log
I also thought it would be a good idea to test this on a server, but upon trying to connect I get this:
And here is the relevant section of latest.log for that.