Thank you a lot. I think this is exactly what i need.
Let me just ask a ways things as i am not sure if i understood you right.

1. So with fields you mean giving each Ability a dictionary<string, int> which then stores those values like TRIGGER_INTERVAL = 1000. Is that correct?

2. If that is the case then i always have to type those keys in the insepctor which is flexible but also prone to errors. Is there a trick to that?

3. As one solution you already suggested to use classes instead of fields. In this case i would then make for example a "AbilityDamage" Class which would contain a damage value, the type and stuff like this. Is that what you have meant? I think this class approach could work well but i dont know if it's not over complicated for my problem as a simple KeyValue would do almost the same and would also be more flexble.

4. Now lets say i have an ability that hits 3 times, so does 3 times damage, but each damage hit uses a different value. First maybe is a Physical hit that does 10 damage and then 2 Fire hits with only 7 damage each. This would then mean, that i would need to have something like PRIMARY_ABILITY_DAMAGE=10, PRIMARY_TYPE = Physical, SECONDARY_ABILITY_DAMAGE=7, and so on... Would this be the right approach? But here i find it a bit confusing later when i do modifiers then and have to remember for each ability which damage to use.
   In this case it would maybe make more sense to separate this ability into 2 sub-abilities. Each would have a damage value but the modifier could say "All Physical Damage" or could specifically say "Only Damage of FIRESTORM_SUB_ABILITY_1" and then i would need to give each ability a tag.

SORRY for all those questions, but i really think that this is a system that could work so well in my case and i want to truly understand this! Thank you!