I have no clue what to do to complete it, or maybe it’s broken. There are two steps
Add Ingredients to the Centraforge ingredients deck which one? I tried resin, gum, and boon, none works, none make this step complete. Start the forging process I’m on round 2 now… so either is broken, or I don’t understand what start in this context mean 
The only mandatory ingredient is setting paste. Can’t do anything without setting paste. That should be what you need to start.
Setting paste, or resin?
Resin is correct. Brain partially shut down on me.
I’ve put it in, out, again… does not work 
What does the objective wording say to do?
Ok, try this. Add setting resin to the deck. Boon paste if you have it. Place the item you want to forge in the forge slot and click start forging.
Does not work. I’ll try on other character when I get to centraforge.
Haven’t got that far yet so it might be bugged.
What did you do before trying to finish the forging session? How many rounds have you ran? What ingredients have you used? Have you gotten any perks? Are you trying to use single setting resin or a stack?
I ran about 10 to 12 sessions, not sure though. Not sure what did i do before trying to finish session. O used lowest tier boon compund, setting resin, and special gum, the tool was a iron hammer. I tried stack of setting resins.
I tried again with iron hammer. Used single special gum, single boon compound, and single setting resin. Still no bueno
Are you getting a forged tool at the end?
Make sure there is a perk on your tool - either a boon or a defect. I’m not sure if you can finish the session if there is nothing created there.
I got Iron hammer that does less damage, but does hit additional one block below the one you’re aiming at. So I guess there is a special thingie. Is it a boon or defect though I don’t know.
Anyway if this is there are some complicated preconditions… lemme go with a classic one 
But seriously I believe it may be bugged. Will update when I try this one another toon… just need to break some glass in my house
UPDATE: On second toon, sadly i wasn’t able to make this trigger either. I say it’s bugged, but maybe there is anyone that can confirm, or deny it?
Hitting additional blocks is a boon. The tool will deal less damage per block (that’s why it shows damage penalty), but more in total if you add all damage from all blocks hit at the same time.