The spell target must be friendly, in line of sight, and in range of the caster.
If the target is flagged PvP, the caster becomes flagged.
The target gains the buff.
Group buff splash - With some exceptions†, all characters in the target's party, including pets, that are within 100 yards of him also gain the buff. This effect is not limited by line of sight. As a result, the caster can buff people at triple the spell range.
† Characters will be excluded from the group buff splash if they are lower than the spell's trained level, or are flagged PvP when the caster is not.
Exclusion by PvP status disrupts raid preparation; typically, the raid will wait for flags to expire, or order the buffing classes to become flagged themselves.