A commission for PTRWhatever.
Dream Eater Merry cross over with Advent Cirno
Fun fact, both series are from the same author. "Advent Cirno" was the work that gets him to becoming a publisher mangaka, and "Dream Eater Merry" was made.

Here is a little dialogue that PTRWhatever created to describe the scenario of this drawing.
Engi: Merry! Heads up! Something's barging into my garden!
Yumejji: Whoever can do that's gotta be pretty STRONG.
Merry: Prepare yourselves!
*CRASH*
China: My my Cirno, wouldn't it have been more appropriate to knock first? ...and uh, couldn't you have shown some restraint Doremi?
Reisen: After the last incident that I had to deal with, I don't think Cirno wanted to wait to jump in on the action.
Doremi: Sorry bout that there my rabbit eared companion.
Cirno: Hehe
Cat Mask: Another Nightmare has shown up, one who seems to like making a dramatic and chilly entrance.
Merry: I hope you all are ready for a pounding and a quick trip back to the dream world. (Fist clenched)
Doremi: My my, I think they may have mistook my dream's path for something else. Sheath your blades fellow nightmare FRIEND.
Engi: What's that you say!?!
Reisen: After a chance incident with Doremi here, I asked her if anything else was going on of note. Her response surprised me. I thought it best if she dropped on on Cirno's next dream.
Cirno: .... and in said dream, she said that there were a certain few other dream demons having some trouble in both the real world and the dream world.
Yumejji: ... and your point is?
Cirno: Big dreams are supposed to be protected and cherished by all! There's no way I could sit idle by and after hearing that they were in danger! If you've got a problem, you've got an ally of me and my blades. I didn't get to be the STRONGEST without first having the strongest dreams! Hehe.
Merry: EH?!?!?! An ally?
Cirno's group: *nods*
Yumeiji: Well then, it is a memorable day when good news shows up.
Merry: Hehe, I like it. *grins*
Cat Mask: Another truth has uncovered itself and the ORIGIN of a new tale is upon us....