What and where from are catalysts?

I mean those:


And what exackly are those "caster modyfiers" for example?

THX in advance.

... de99ial, is that really you? They come from Metamorph, the league that prompted you in making that post about Darkness ;)

Catalysts are rewards tied to Metamorph. Some organs can make the metamorph yield these useful little currency, which can be applied to any ring, amulet and belt. Yes, even uniques. They work as other quality-enhancing items: they boost +5% on Normal items, +2% on Magic and +1% on Rare and Unique, for a maximum of 20%. Applying another type of Catalyst will fully remove any precedent quality from the other Catalyst, and some currency can remove a bit of quality (examples are Augmentation and Exalted orb - be wary of the new description)

As for the "caster modifiers", it regards any modifier tied specifically to spells. This means, for example:
> % increased cast speed
> % increased spell damage
> % increased spell critical chance
> % adds x-y damage to spell *
> spells have +x% increased critical chance

* this only work if specifically stated. A bonus that boosts both attack and spells (like the "add x-y damage" and the "add x-y damage against ailment-affected enemies" will NOT get boosted by a Catalyst)

EDIT: oh right, forgot about the recipe. If you find yourself too full of a certain catalyst, you can sell 3x the same catalyst for a 1x random catalyst (not of the type you are selling)

Yes its me ;)

I asked that question because to me that "caster modyfiers" or any other description from catalysts are too vague to be simple in understanding. I just dont get them.

Don't worry, you are not alone. Some Exiles are still confused by that wordings, and someone else believe there is a catalyst for boosting every single modifier a jewellery can yield.

If you need a better grip or a more comprehensive list, however, you can use fossils. There are fossils that play with the chance for "caster modifiers" and "attack modifiers" to yield on a certain item. I guess GGG expected players to have fiddled enough with those fossils to recognize at glance what makes a modifier "caster" or "attack"

For the record, Attack Modifiers follow the same logic as the Caster modifiers, just replace "cast" with "attack" and "spell" with "attack". Oh, this also means it includes bonus like "add x-y damage to attacks against [ailment-affected] enemies" or "+x% elemental damage with weapons / +x% elemental attack damage"

In that case there are items that are Catalyst-resistant because using any of them on such item wont give bonus.

Catalysts can only be applied to rings, amulets and belts. Of course, they have to be non-corrupted for them to work. Talismans, since they are implicitly corrupted, cannot have Catalyst quality, nor anointments
In order to "feel" the Catalyst's effect, the item has of course to have at least 1 modifier of the subclass it boosts. It's useless to give a Fertile Catalyst on a Chain Belt with not lifeRegen, lifeLeech, maxLife or any life-related bonus

EDIT: Sorry, it does have a sense. When you augment, or exalt, an Item with catalyst-related quality, some of that quality is removed for a higher chance for a bonus of that group to appear in that item. Much like the "quality affects chance for 6L" in other equipments

My main issue with those is naming. I tried several different catalysts on this ring and none changed a thing:


And i tested almost all of them.

Prismatic Catalyst would increase the cold resistance on it.
Fertile Catalyst should increase the mana stuff.

The quality goes up to 20%, you're not gonna notice 1%

Also you could use a blessed orb to go from 20% to 30% on the cold res. More likely to notice the change on that

Just would like to share that different mods seems have different increments when you apply catalyst.



For example, the "all resistance" mods will go up by 1 for every 10 Prismatic Catalyst. But the "chaos resistance when on low life" will go up by 1 for every 4 Prismatic Catalyst.

If anyone could share how much increment for each mods, that would be nice!

increment is not different - it's the same percentage for each of them.

If I apply Armourer's Scrap, whose effect is "+1% increase local base defences per 1% Armourer's Scrap quality", to a Vine Circlet (6 ES) or a Hubris Circlet (76), both to 20% quality, I'll have a
6 * 1.2 = 7.2 = 7 ES Vine Circlet and a
76 * 1.2 = 91.2 = 91 ES Hubris Circlet

Vine Circlet gained only 1 ES, whereupon Hubris gained 15, but the quality is the same

Same goes for Catalyst Quality. Quality, for the sake of boosting modifiers magnitude, works better if the numeric value is already high. The higher the base, the higher the boost

So, in order to understand how much your bonus will gain from modifiers, just multiply that base, raw value for 1.2. If you feel that would change significantly that item's power, then go and dig in it. Otherwise, keep them for something else