From Guild Wars Wiki
Battle Lion is a common term used in high level
GvG/
PvP play, which refers to the most forward and aggressive player on a team. Battle Lions are not to be confused with players who are out of position or overextended. They push forward for a variety of reasons including attempts to pressure and delay enemy flag carriers. In addition they are often used to draw as much aggro from enemy
NPCs at
VoD, so that monk team-mates only have 1 key team-mate to
heal and
protect.