On Hard Mode, K'ril Tsutsaroth has a few changes in his mechanics, such as no longer having an explicit weakness to fire spells, as well as no longer using his Prayer smashing ability. Like all other hard mode God Wars Dungeon bosses, K'ril can bind players for 250 damage if they are under him. His health increases to 100,000 from 55,000, and he has three special attacks he can activate any time during the fight. He is still poisonous and his bodyguards act as normal.
Compared to the other hard mode battles, K'ril is arguably the easiest of them all due to the effects of the slayer helmet if on a greater demon task and attacks that are fairly easy to avoid.
Note: For unknown reasons, K'ril's magic attack animation is disabled during hard mode; instead, he uses his melee attack animation for it.
K'ril Tsutsaroth will yell Run, coward!, and after a brief pause, will charge towards the player he is targeting until he hits the wall. Simply move to the side and watch K'ril bash his head (he takes some damage from this), then continue attacking. Being caught in this attack (essentially being under him while he charges) will result in moderate damage. K'ril is immune to damage while he is running or hitting the wall. An in-game message will tell the player K'ril prepares to charge.
When K'ril says You cannot stand against Zamorakian might!, he will summon an earth spike under the player he is targeting. Players will be notified when he summons an earth spike by an in-game message stating K'ril Smashes his blade into the ground, which bursts into spikes from the impact. While on the spikes, the player will receive 990 damage every two ticks unless they move off it. Players can lure K'ril over the spike; if he stands over it he will take rapid but weak bleeding damage, between 100-500 every tick. After a short time, the earth spike will disappear.
K'ril Tsutsaroth may become enraged with the player he is attacking, and will shout Die in the name of Zamorak! K'ril will swipe his scimitars in front of him for about 5 seconds, hitting all players in the area in front of him with rapid Magic and Melee attacks. An in-game message will tell the player K'ril becomes enraged, swiping at you with wild but inaccurate strikes. You should try to avoid them. These strikes will hit all players K'ril is facing once per tick for about 8 ticks; this also applies if he is moving during that time.
Players are advised to Surge away to avoid the majority of the attack, after which the fight will resume as normal. These attack are able to hit slightly over 2,000 damage each. If you are unable to run away, casting Anticipation or Freedom is recommended to prevent being bound in place if you run under him, as well as using either Protect from Melee/Protect from Magic (or their Deflect counterparts) and either Debilitate or Devotion to minimize damage; Immortality is also a viable option if players are taking too much damage.
While K'ril is in his enraged mode, he will swing his blades wildly while running towards the player if he cannot reach them. You will know when he is finished with this attack when he returns to his normal walking animation.