What is the new feature or improvement?

The totem of illusion and totem of freezing from "Friends and Foes" mod are not supported and do not go into the slot. Can they be added?

What kind of effects do those items have?

Totem of freezing is a regular totem but entity who kills is damaged and frozen effect is given to it(the one from powdered snow)
Totem of illusion is similar to a regular totem, but it gives the player invisibility effect and makes a large amount of exact copies of the player around them which mobs target.

It looks like Friends & Foes have added this compatibility on their end.