Buffy: Season Ten Volume 4: Old Demons — Christos Gage

Buffy needs serious backup. With an ultimate Big Bad, Archaeus, connected to so many from the Slayer's past, she's calling in reinforcements -- and saying to hell with the awkward consequences. As the gang get closer to Archaeus, the extent of his plans and their connection to the new rules of magic are revealed. Collects Buffy Season 10 #16�"#20.
“The most consistently good of the post-series Buffy comics to date.” -- Comic Book Resources