What is the green/red affinity between a dragon and a troop type?

Every dragon has an affinity for each troop type, shown as a color:

• 🟢 Green (Positive) = +20% to the dragon's stats (and a boost to siege damage). Excellent.
• ⚪ Neutral = no effect, no bonus and no malus.
• 🔴 Red (Negative) = a penalty to the dragon's stats.

You see these colors on the Army Builder screen, to the left of each dragon's portrait, for the troop type you selected. That's the reliable source to check — don't eyeball it.

⚠️ Don't confuse affinity (+20%) with the troop matchup (±7%, see the troop triangle). Affinity is far stronger. Simple rule: when two dragons are equal on the right type, take the green one.