21 cards where (the artist name includes “william” and the artist name includes “o'connor”)

Beast (Eventide Tokens #3)
Crown of Flames (Tempest #169)
Elf Warrior (Game Night: Free-for-All Tokens #9)
Fencer Clique (Morningtide #33)
Forced Fruition (Lorwyn #66)
Graceful Reprieve (Modern Masters 2017 #8)
Knight (Time Spiral Remastered Tokens #5)
Moonglove Winnower (Lorwyn #126)
Persuasion (Tenth Edition #95)
Pouncing Wurm (Planar Chaos #136)
Razorfin Abolisher (Eventide #28)
Riftmarked Knight (Time Spiral Remastered #38)
Safehold Sentry (Shadowmoor #22)
Savage Conception (Eventide #75)
Shade of Trokair (Time Spiral Remastered #42)
Spiteflame Witch (Shadowmoor #197)
Storm Front (Tempest #259)
Streambed Aquitects (Duel Decks: Merfolk vs. Goblins #18)
Sunrise Sovereign (Commander Anthology Volume II #121)
Thorntooth Witch (Lorwyn #144)
Vengeful Firebrand (Morningtide #111)

Though this query has ended, its relics still slumber in New Argive.