Confidence:StrongSolidPlausibleTentativeSpeculative

• Baron Helmut Zemo

  BBB

  Legendary Creature — Human Noble VillainB

  Copy engine: one card makes a copy of a creature every turn, and the other's enter-the-battlefield effect rewards each copy. Real, repeatable value — the partner can't untap or re-enter the copier, so it never goes infinite.
• Basri, Tomorrow's Champion

  W

  Legendary Creature — Human KnightW

  Basri, Tomorrow's Champion has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Morska, Undersea Sleuth

  GWU

  Legendary Creature — Vedalken Fish DetectiveGUW

  Both cards trigger when you draw a card — they fire together.
• Unearth

  B

  SorceryB

  Unearth has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Flame Blitz

  R

  EnchantmentR

  Flame Blitz has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Jolted Awake

  W

  SorceryW

  Jolted Awake has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Decree of Annihilation

  8RR

  SorceryR

  Decree of Annihilation has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Ratadrabik of Urborg✓

  2WB

  Legendary Creature — Zombie WizardBW

  Copy chain: one card creates hasty copies of a creature whose ability or ETB the partner exploits — the canonical Kiki-Jiki / Splinter Twin pattern.
• Zameck Guildmage

  GU

  Creature — Elf WizardGU

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• Decree of Pain

  6BB

  SorceryB

  Decree of Pain has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Neutralize

  1UU

  InstantU

  Neutralize has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Resounding Thunder

  2R

  InstantBGR

  Resounding Thunder has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Boon of the Wish-Giver

  4UU

  SorceryU

  Boon of the Wish-Giver has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Spectacular Pileup

  3WW

  SorceryW

  Spectacular Pileup has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Webstrike Elite

  GG

  Creature — Insect ArcherG

  Webstrike Elite has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Intimidation Tactics

  B

  SorceryB

  Intimidation Tactics has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Sage of Fables

  2U

  Creature — Merfolk WizardU

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• Iron Spider, Stark Upgrade

  3

  Legendary Artifact Creature — Spider HeroC

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• Viashino Sandsprinter

  1RR

  Creature — Lizard WarriorR

  Viashino Sandsprinter has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Akroma's Vengeance

  4WW

  SorceryW

  Akroma's Vengeance has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Pest Control

  WB

  SorceryBW

  Pest Control has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Ray Fillet, Man Ray

  3U

  Legendary Creature — Fish MutantU

  Draw pair: both cards engage with card draw. With a damage-or-draw trigger between them they form a draw engine.
• Unpredictable Cyclone

  3RR

  EnchantmentR

  Unpredictable Cyclone has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.
• Dino DNA

  1

  ArtifactC

  Copy engine: one card makes a copy of a creature every turn, and the other's enter-the-battlefield effect rewards each copy. Real, repeatable value — the partner can't untap or re-enter the copier, so it never goes infinite.
• Easy Prey

  1B

  InstantB

  Easy Prey has cycling, and Stalwarts of Osgiliath pays off whenever a card is cycled — the Astral Slide / Lightning Rift engine shape.