I just understand gain and covert.

It does what is says on the tin, it splits your damage into the three elemental types and adds a little more on top for the trouble

Generally speaking if you don't immidiately see that it would be good for your build then it's probably not

You get stronger and all your damage gets divided evenly between fire cold and lightning

You gain 18% of your elemental (fire, cold, lightning) damage as extra damage. Your elemental damage is now split evenly 3 ways across fire, cold, and lightning damage.

This is a net gain if you are scaling all elemental damage instead of one type, and/or if you are not looking to scale one ailment (primarily shock).

Unrelated to your post but put another rune in there. The iron rune us next to useless.

Convert of each of your elemental damage happens first, then the new values of that get that Gain values next. It's good on certain builds like utilizing Trinity to have a 100% uptime, while the spirit cost is high, the return is a Moretiplier and skill speed which is a huge boost in general.

The chance is low but you can get to total damage convertion to go above 100%

So in theroy the could net you up to alt least 30% extra damage just from convertion before any extra or othere sources of increase I say 30% because it lokkede like 40% convertion per element was the top but i could be wrong on that

First, this will do nothing for physical damage. Yes you need to do elemental damage to get any benefit.

The bottom 3 lines tell you that 99% of your elemental damage will be split 3 ways between cold, fire, and lightning. Whatever elemental damage you did will be evenly distributed across the three elements (even if you originally did zero for one of them).

If you originally did 100 cold, 200 fire, and 300 lightning you would now do 200 cold, 200 fire, and 200 lightning.

Top 3 lines are gain as extra. If we still assume you’re doing 600 elemental damage per above, you’d now do 212 cold, 210 fire, and 214 lightning. Base damage * 1.06 for cold, 1.05 for fire, and 1.07 for lightning.

After playing with these gloves and trinity this league I will probably never do it again.

Very unfun to balance flat damage on rings/weapons,sources as extra, and increases.

Getting very specific heart of the well/ against the darkness is also a pain.

Edit per order of opperations correction:
So basically, as I understand it, you split your total elemental damage between all three elements, 33% each, THEN, after that, all of your total elemental damage gains extra damage as cold, lightning, and fire for those percentages of the base total.

As I understand this one, it's not great, but has niche uses at low-mid levels during the campaign.