An easy to understand guide on how to get Dark Offering, Devil’s play and Collective Effort This guide contains spoilers!
Dark Offering
To get Dark Offering you simply need to get both halves of the Broken Obal
They can both be purchased in the bottom right slot of Grimora’s trader for foil
After you have both cards, simply place them in the same orientation as above in a fight and you will get the Ancient Obal. If you can’t do it in a fight use the training dummy on the second floor of the tower.
After you have the Ancient Obal head down the stairs in Grimora’s crypt and interact with the coffin in the corner
You can then go retrieve the Bone Lord’s Horn and Femur
Devils Play
In order to get the Devil’s Play achievement you need to do 666+ damage in a single attack
First assemble a deck that contains these cards
A Bone Heap an Energy Conduit and the Bone Lords Horn
Aswell as 1 more conduit card, it doesnt matter which one you choose
After that you can fill the rest of your deck with anything, extra’s of your cards, skeletons, or mox’s make good picks though
Once you are in the fight you don’t need to worry much as none of the enemies actually attack.
Skip your turn until you have all of the cards you need then place them in this order
Misc. Conduit -> Bone Lord Horn -> Bone Heap -> Energy Conduit
(you can use stim wizard instead of the bone lord horn and bone heap but you got the horn so you wanna use it)
Collective Effort
To get Collective Effort you need every card in the original Inscryption
Since you already got Dark Offering and Devil’s Play, this part is really easy! Any cards you don’t have can be bought with foil except for the kraken card and to get that all you need to do is wait at the dock for a short bit and a tentacle will rise out of the water.
Interact with the tentacle and then head to the tower
On the top floor of the tower there is a room to the right, go into that room and wait for a bit again
a tentacle will pop out of the bathtub
Interact with that tentacle and it will go down and come back up with a card
Any other cards you want can be found in card packs, if you are unsure what cards you are missing the traders room on the bottom floor of the tower has a book you can check that shows you all your discovered cards.