Broodscale Mirror Cavern of Souls Impact

In the Broodscale mirror, Cavern of Souls in the sideboard raises win rate the most. Sire of Seven Deaths is the biggest main-deck card. I couldn't find a "mono green broodscale" archetype with Modern data. The archetype I used is "Broodscale", the only Broodscale archetype with Modern matches (the database lists it as BG). The "broodscale combo" archetype has no Modern matches.

The mirror sample is about 983 decisive match results (draws excluded), from July 2024 to October 2026. Each match is counted once from each player's side. I only compared cards with at least 60 matches both with and without them.

Biggest win rate gains in the mirror (with the card vs without):

• Cavern of Souls (SB): 57.4% vs 48.9%, +8.5 points (136 matches with it)
• Sire of Seven Deaths (main): 55.7% vs 48.4%, +7.3 points (219 matches)
• Delighted Halfling (main): 55.6% vs 48.7%, +6.9 points (187 matches)
• Yavimaya, Cradle of Growth (main): +3.8 points
• Gemstone Caverns (main): +3.8 points

Caveats:

• These are correlations. Players who run these cards may just be better players or running different builds.
• The samples are small, so a gap of a few points could be noise.
• Cavern of Souls shows up in the sideboard in only a minority of lists.

Sources: 893 Broodscale tournaments in the window, 68% MTGO and 32% Melee. Recent events:

• Modern RC Super Qualifier
• Modern Challenge 16
• Modern Challenge 64