Every hero has an Attack attribute, which you can see on the hero screen.
This increases when you
- Level up the hero (using crystals and coins) / promote the hero (using Hero medals and coins)
- Star up the hero (using Hero shards)
- Get Good Shot upgrades
- Get hero-specific attack bonuses on promotions (e.g. Firebug gets +100 Attack at Level 10 and 7% at 30)
- Get Attack skills (using Rings and coins) - some are fixed amounts and some are percentages. Note that Boss Damage Bonus skill will not show here
- Get all-hero bonus by promoting other heroes (e.g. Miasma at Level 20 gives +100 attack to all heroes) - however, enemy specific bonuses (e.g. Blazia’s +5% for Ground Enemies at Level 20) don’t apply
You can estimate the Attack (and Health) using the Hero Stat Simulator