The basilisk casts a petrification cast, a narrow cone, on players in front of him. At 75% 50% and 25% the basilisk enrages and deals one-hits. Two hits from the ballistae will calm him down and remove the enrage buff.
Tail swipe: physical AoE to the back, shatters petrified players
Tainted Blood: AoE area which debuffs players (less healing, less damage, mana and stamina drain) but also allows priests Steadfast Faith with the Petrify Purge effect: Priests can free purge other players petrification with SF for 18.5 seconds.
Acid decay: AoE dealing damage, the basilisk spits it at the end, beginning at 12%.
The basilisk is tanked by several tanks on the impact holes of the ballistae. The tanks turn him roughly towards the wall with the entrance gate. The tanks stand side by side, such that as few as possible are petrified when he casts.
The ranged damage camp is always between the current impact hole and ballista.
Healers get the debuff from the blood and purge the petrified as quickly as possible.
Melee DD’s can attack the basilik from the back, coming from the damage camp, if the basilik is well positioned. They easily disturb pathing, so withdraw when he dances around.
At 75%, 50% and 25% the ballista gunner shoots when the basilisk rears up. Then the basilisk is pulled to the other impact hole and the second shot is fired. The basilik then looses his enrage buff and the tanking goes on.
During the enrage phase the basilisk deals one-hits even on tanks. DDs stay away and cease damage, as the basilisk also has an aggro reset.