引用自 MystoganCy：

it reads as When a skill triggers, deals magic damage protortional to effect value to a random enemy. so what exactly is 'skill' i had this synergy before and i didn't activate the effect a single time, can someone tell me how this works

The skill is the skill of the characters on the field, it just that. Everytime a character use their skill the passive will trigger, but the visual is a bit lacking so you may miss it, but you can still see the damage being done.

im not even seeing the damage

I thought I was the only one tripping when I didn't see the damage from the magic bullet everytime my characters use a skill. Its probably a bug that needs to be fixed later on.

I just had Forest up and running and I was seeing the damage every time. It's a pink number that comes up after the character uses a skill.

Bit of a bump.

I think I have the same issue as OP, it does not seem to trigger. 250DMG is a lot, I should notice that on the HP bars right away. Is this a known BUG?

It's not 250 damage. The number is a percent. At level 1 it does 100% of your attack stat as magic damage. Level 2 does 250% of your attack stat as magic damage.

Forest is easiest to see with non-enemy attack skills (for example, Reno/Mustio skills do not affect enemies, but in Forest comps, you can see that purple damage numbers will pop up even when they're targeting allies).

Otherwise, because the numbers stack on top of each other, the Forest damage proc can get covered up by other damage numbers.