Alright, so I messed around with the ‘poe fertile catalyst’ thing today. Let me walk you through what I did, step-by-step.
First off, I grabbed a bunch of Fertile Catalysts. You gotta have those, right? I went vendor-diving for the cheapest ones I could find. Saved a few chaos doing that, felt good.

Next, I had to figure out what I actually wanted to enchant. I had this one amulet sitting around, nothing special, but it had decent life and resists. Figured, “Why not?” So, I chucked it into my inventory ready for some action.
Then came the fun part – actually applying the Catalyst. I right-clicked the Fertile Catalyst, and then clicked the amulet. Poof! The amulet got the “Enchanted” tag with the added implicit modifier for increased experience gain, which wasn’t exactly what I was going for, but hey, it’s something. I was hoping for something more juicy like increased life or mana.
Okay, so now I had an enchanted amulet with an implicit mod. Time to see if I could juice it up even more. I started running some Blighted Maps, hoping to drop another Fertile Catalyst. RNGesus wasn’t exactly on my side, but after like five maps, bam! Another one dropped.
Repeated the process. Right-clicked, then clicked the amulet. Same thing, experience gain again, felt like a slap to the face. Seriously? It’s like the game was laughing at me.
I wasn’t giving up that easily. After a little bit of grinding, I got another amulet which had some good stats on it. Did the same process, right click the catalyst, left click the amulet, and got a better increased life implicit! I think I might use that one!
So, final thoughts? The Fertile Catalyst thing is alright. It’s kinda random what implicit you get, and it can be a bit of a gamble. I think its worth it if you’re trying to min-max some gear, and you have the currency to burn. I did manage to improve one of my amulets so I guess it was worth it.