A successful hit is where during combat an attack overcomes its target's Defence. It is unlikely but possible to produce a 0 as a successful hit.
This can be better explained by considering the following:
For every attack, there are two stages.
- Stage 1: Roll the attacker's offensive bonuses against the target's defensive bonuses. If true, proceed to stage 2. If false, produce a 0 (splash for player Magic attacks). This is not a successful hit.
- Stage 2: Roll a hit ranging from 0 to the attacker's maximum hit.[1] This is a successful hit, even if a 0 is rolled.
A damaging spell cast by a player that hits a 0 which does not visibly splash is always a successful hit, and if it has additional effects (such as freezing for ice spells or chance to lower the target's Strength if Ahrim's equipment is worn) they will occur as usual.
Some passive effects only occur during successful hits - such as Guthan's and Karil's equipment set effects, as well as the serpentine helm where there is a chance to envenom the target.
The Saradomin godsword's special attack will only replenish the user's Hitpoints and Prayer points on a successful hit; likewise, the Zamorak godsword's special attack will only freeze a target on a successful hit. However, the dragon warhammer's special attack has to deal damage in order to lower the target's Defence level even if a successful hit of 0 is rolled.[2]
The special attacks of the granite hammer, dark bow, magic comp bow, magic longbow and seercull always result in a successful hit.
The Ranged and Magic attacks of the Kalphite Queen will always result in a successful hit.[3]