The C Series - Crossfire, Conclusion and ClownMaster - are an alternate ending to the Rozen Maiden anime series by doujin artist Raid Slash. As such, they might not make much sense unless you have seen at least the original Rozen Maiden series, and the second season, Träumend.
The story of the C Series diverges somewhere in the final episodes of Träumend, where for reasons unexplained, Shinku is killed, while at least Suiseiseki and Suigintou survive. The Alice game then ends without a winner.
The chapters were actually published in the order Conclusion, Crossfire and ClownMaster. I have chosen to present them here in a somewhat more chronological order.
Some notes on the translation follow:
On Botan's name: Botan is written as "牡丹" in kanji, meaning "peony". However, "botan" is also a loan word for "button", and "Button" seems an appropriate name for a doll. It's not clear if this is intentional or not.
On "Träumend": The author uses "träumend" as the reading for the word "dream" in Conclusion - "To make sure that you never see another idiotic träumend again." "Träumend", however, actually means "dreamingly" in German, a fact the author does acknowledge in the afterword.
On Mangekyou's name: Mangekyou is written as "万華鏡", which means "Kaleidoscope". The significance of the name should be obvious. "万華鏡" can also be read as "Bankakyou", and there is no indication which pronounciation the author intended for the name, so "Mangekyou" was arbitarily picked.
On "Herz König": This is German for "King of Hearts", another Alice in Wonderland allusion.
The afterwords were left untranslated entirely out of laziness, as they are quite wordy. Apologies.