There were two types of Cleric heals. One type was a heal over time and had a cast time. This was what players commonly referred to when they said heal. This type was split into three different kinds, small heal, great heal, holy heal. The longer the cast time, the greater the heal. The casts made by Clerics were different from Ninja hand seals, which would be improved with better skill. For these casts, the only thing that could be done was to press the skill faster. The cast time could only be decreased with the character's spirit attribute and certain equipment.
The other type of heal was an urgent rescue type. This type of heal was called cure and was split into three different kinds: small cure, great cure, holy cure. Cures didn't have a cast time and were considered instant casts. However, they had very long cooldowns and it wasn't possible to only rely on these to recover health. As a result cures were mainly used in emergencies, while heals were the ones mainly used.