Yes, you will be able to turn them in to the next iteration of Treasures of Halloween as you could between Doom & the Kotl City.@Mesanna, @Kyronix
Any chance of an answer on this:
When we started the Kotl City spawn this year for turn-in arties, we could also turn in previous arties from Dungeon Doom last year. Will we be able to turn in the Kotl arties next year like we did the Doom ones, or do we need to use up what we have collected before this Kotl City event ends next month?