To find an actual chance to hit, the easiest way is to test it out and look at the combat log (logs -> combat log). It will show you the chance to hit at each combat (and how many HP are removed).
Two full strength units, though, the chance to hit should be (attacker strength) / (attacker strength + defender strength), I believe, with any modifiers added appropriately.
Two full strength units, though, the chance to hit should be (attacker strength) / (attacker strength + defender strength), I believe, with any modifiers added appropriately.
Comment