From the railroad blockage to the Witch’s Hut
A cave seal, an underground passage and a guard each use a different trigger. Start at the railroad so the game knows which conversation you want from Krobus.
Trigger the Wizard’s request at the railroad
Finish the Community Center route or the Joja community development route, then visit the Railroad north of the Mountain. Look for the Wizard’s scene about the blocked cave. If you have only opened the railroad itself, completing that early access milestone does not unlock the Witch’s Swamp. Check the journal for Dark Talisman before making a trip to the Sewers.
Collect the talisman in the Mutant Bug Lair
Use the Rusty Key to enter the Sewers. Talk to Krobus during the active request to open the northwest passage. Go through the new opening with a weapon and healing food; flying insects can interrupt a chest interaction. Follow the available walkway to the chest, collect the talisman and return to the cave seal at the railroad. Showing the item there opens the way into the swamp.
Move the henchman and return the ink
Carry Void Mayonnaise into the swamp and give it to the Goblin Henchman blocking the path. Ordinary Mayonnaise is a different item. One dependable preparation is to buy a Void Egg from Krobus and process it in a Mayonnaise Machine. Once the guard leaves, enter the hut, take the Magic Ink and bring it back to the Wizard. If you can enter the swamp but cannot reach the hut, solve the guard step instead of retracing the bug lair.