"This Man... This Demon!"
May 1969
Diablo uses Valeria to convince Doom to join forces with him
reprinted in
*
Essential Super-Villain Team-Up TPB #1
(cover and spread omitted from GSSVTU #1 reprint only)
2004, in collection
(2004*)
*
Giant-Size Super-Villain Team-Up #1
"Encounter at Land's End!", reprints
March 1975
(3/1975)
Namor rescues Doom, and the two consider a partnership