Mirran Mettle

an artifact you control — 3,641 cards in the game can cause this (Mirran Mettle is one).

1. Chimeric Egg — Chimeric Egg counts toward the 3 or more artifacts Mirran Mettle needs
2. Prowl, Stoic Strategist // Prowl, Pursuit Vehicle — Prowl, Stoic Strategist // Prowl, Pursuit Vehicle counts toward the 3 or more artifacts Mirran Mettle needs
3. HYDRA Assault Robot — HYDRA Assault Robot counts toward the 3 or more artifacts Mirran Mettle needs
4. Tome of Legends — Tome of Legends counts toward the 3 or more artifacts Mirran Mettle needs
5. Canoptek Spyder — Canoptek Spyder counts toward the 3 or more artifacts Mirran Mettle needs
6. Cloudstone Curio — Cloudstone Curio counts toward the 3 or more artifacts Mirran Mettle needs
7. Traxos, Scourge Eternal — Traxos, Scourge Eternal counts toward the 3 or more artifacts Mirran Mettle needs
8. Alibou, Ancient Witness — Alibou, Ancient Witness counts toward the 3 or more artifacts Mirran Mettle needs
9. Foot Chopper — Foot Chopper counts toward the 3 or more artifacts Mirran Mettle needs
10. Lux Artillery — Lux Artillery counts toward the 3 or more artifacts Mirran Mettle needs

3,631 other cards care about it too. These are the ones with the most connections.

an instant is cast — 3,931 cards in the game can cause this (Mirran Mettle is one).

When Mirran Mettle is cast:

1. Lunar Mystic — draws you 1 card
2. Ojer Pakpatiq, Deepest Epoch // Temple of Cyclical Time — grants rebound
3. Repeated Reverberation — copies an ability
4. Bill Potts — copies an ability
5. Riku of Two Reflections — copies a spell
6. Sword of Wealth and Power — copies a spell
7. Lilah, Undefeated Slickshot — gets +1/+1
8. Gale, Waterdeep Prodigy — brings a card back
9. In the Eye of Chaos — counters a spell
10. Niblis of Frost — taps a creature an opponent controls

427 other cards care about it too. These are the ones with the most connections.

anything is cast — 31,128 cards in the game can cause this (Mirran Mettle is one).

When Mirran Mettle is cast:

1. Windrider Wizard — draws you 1 card
2. Relic Amulet — puts a charge counter on itself
3. Rockslide Sorcerer — deals 1 damage
4. Umara Wizard // Umara Skyfalls — grants flying
5. Alania, Divergent Storm — makes an opponent draw 1 card
6. Umara Mystic — gets +2/+0
7. Master of Winds — triggers

5 other cards care about it too. These are the ones with the most connections.