| Siege of Towers | GPT-76 |
| Siege Wurm | GRN-144 |
| Siege Zombie | DBL-121 |
| Siege-Gang Commander | DMR-136 |
| Siege-Gang Lieutenant | M3C-113 |
| Siegecraft | KTK-23 |
| Sigil of the New Dawn | UMA-35 |
| Sigil of Valor | ORI-239 |
| Sigiled Starfish | ORI-73 |
| Sign in Blood | P10-3 |
| Sign in Blood | M10-112 |
| Signal Pest | MBS-131 |
| Signpost Scarecrow | ELD-231 |
| Silence | TSR-302 |
| Silent Observer | SOI-86 |
| Silhana Ledgewalker | PCA-77 |
| Silkweaver Elite | AER-125 |
| Silumgar Butcher | DTK-122 |
| Silumgar Sorcerer | DTK-76 |
| Silumgar, the Drifting Death | FRF-157 |
| Silver Knight | SCG-23 |
| Silver Myr | MRD-241 |
| Silverbeak Griffin | M19-285 |
| Silverchase Fox | BBD-106 |
| Silverflame Squire // On Alert | ELD-31 |
| Silvergill Adept | RIX-53 |
| Silvergill Douser | LRW-87 |
| Silverglade Elemental | MMQ-269 |
| Silverglade Pathfinder | MMQ-270 |
| Silvos, Rogue Elemental | ONS-282 |
| Simian Spirit Guide | PLC-122 |
| Simic Guildgate | RNA-257 |
| Simic Locket | RNA-240 |
| Sinew Sliver | PLC-30 |
| Singing Bell Strike | KTK-55 |
| Sink into Takenuma | SOK-89 |
| Siren Stormtamer | XLN-79 |
| Sisay, Weatherlight Captain | MH1-29 |
| Skaab Goliath | ORI-74 |
| Skarrg, the Rage Pits | PCA-127 |
| Skeletal Changeling | LRW-140 |
| Skeletal Scrying | C14-162 |
| Skeletal Wurm | ROE-127 |
| Skeleton Archer | M19-118 |
| Skewer the Critics | RNA-115 |
| Skinthinner | LGN-80 |
| Skirge Familiar | USG-157 |
| Skirk Commando | A25-150 |
| Skirk Fire Marshal | ONS-229 |
| Skirk Prospector | DOM-144 |