This mod lets you configure groups of armor items and status effects, and then players will get those effects while wearing that armor.
This is for modpack authors - you need to configure it to make it do anything good.
Also consider the mod Fx Control, a much more general and configurable mod that applies effects when certain conditions are met (but not when wearing specific armor, I think).
The default config has some examples. Basically you write rules like this:
minecraft:diamond_helmet+minecraft:diamond_boots=minecraft:invisibility/2+minecraft:poison/3/400/0
This rule says: if a player wears a diamond helmet and diamond boots at the same time, give them Invisibility 2, and also give them Poison 3 for 20 seconds (400 ticks), and the last 0 means "not hidden" i.e. they'll have bubble particles and it'll show up on the top-right of the screen. So the poison will stay for 20 seconds after they take off the helmet. For the invisibility, we left off the duration and hidden-or-not number, so they'll default to 10 seconds and hidden. Note that "hidden" effects can still be seen when inventory is opened.
This also works with armor and status effects from other mods.
Planned extensions:
- Curios compatibility.
- Allow it to detect items held in hand, or items in inventory. So you can have e.g. a talisman that gives fire resistance while it's held.
- I haven't found any good Forge 1.16 mods that add lots of status effects. I'm working on a mod that will add hundreds of them.
- Write a mod to prevent hidden effects from showing on inventory screen.