×You can get two wrathwings almost immediately. I then moved NE to about point 1 then south, getting a third wing on the way, and SE to point 2 where most of the rest were dealt with.

×keep the goblins together one on top of the other, at the bottom of the room

× to kill them, you'll have to trap them against a vertical wall. But you also need to separate them

×I used the wall of three blocks just to the west of the X.

×if you move from the west side of the wall, around the north end, to the east side, one goblin will follow you and the other will get trapped on the west side.

×after that, I trapped the remaining goblin on the westernmost wall at the bottom of the board.

×In my original solution a goblin was the fourth to die when he was blocked by a group of three wraithwings (of the four remaining) coming down behind him from the NW but I wasn’t able to repeat this. In another solution a goblin was the third to die, to the north of the wall NE of the trapdoor, but again I found this difficult to repeat. After some ten goes I found that the most consistently repeatable method was to deal with the wraithwings first and leave the goblins to last – I am now able to repeat this at will. stigant’s method looks interesting and I will try it after this. He doesn’t say how many wraithwings are still alive but there must be some in order to trap the goblin in that position.

×With the two goblins to your east travel NW along the diagonal that ends at 3. Go just to the north of the horizontal wall then south to point 4 – the goblins should be lined up to your north. Travel NE and the rest should be trivial.

×the first goblin comes around the wall

× the second goblin came around right after I killed the first one