Instructions
Visit the supply room and make sure that you are stocked up on a few key items needed to mount a successful offense. Bandages heal you and increase your energy levels after enemy attacks; Barricades slow down enemies who are pursuing you; and Exploding Potions blow up the other team's Barricades so that they won't stand in your way of the flag.
Don't go it alone. Work together with other team members when going on the offense. As you approach the enemy castle, you will encounter other players surrounding their flag, defending it from capture. You will likely take a lot of damage in the course of penetrating these defenses, so it helps to assign jobs to team members to keep everybody relatively safe. A few people should work primarily to blow up barricades. A few should come along solely to heal other players with bandages. Still, others might come along to set up barricades in the enemies' path.
Use the underground passageways to get past enemy defenses. Although going directly toward the castle via the main path is the fastest route to the enemy flag, it is also the most dangerous. The underground passages -- there are four located in different parts of the map -- are safer because these will take you past the enemy Mages who stand on the castle walls and would otherwise bombard you with harmful spells.
Stick close to high-level team members if you are a low-level player. If you have achieved level 43 or higher in prayer, then most harmful attacks from Mages, Rangers and Warriors will not harm you. Such players, when stocked with the proper supplies, are quite dangerous on offense and can capture enemy flags more easily than most.