A guide for killing k'ril tsutsaroth
Wear your best melle gear with a stat hammer for spec. Take super pots.
Wear a whip or dragon hasta.
Activate melle protection and melle piety.
Statius hammer spec him twice.
Whack with dragon hasta/whip/zs
Every once in a while, he will use a powerful magic attack that can hit 40+, but it's better to use melle protection, since two of his 3 minions and K'ril himself use melle attacks primarily.
You can bring a zs if you want, but I would rather have an extra food. You can use the altar to restore prayer about once every 5 minutes, or right click ----> teleport in an emergency.
A guardian angel and at least 70 prayer is highly recommended.
Inventory:
4x prayer potion or super restore potion
1x Statius' warhammer
1x Teletablet in case of emergency
1x super strength
1x super defense
1x super attack
19x manta ray, or 18 mantas and z spear
My gear:
Void knight helm
Void knight top
Void knight bottoms
Void knight gloves
Strength amulet (T)
Steadfast boots
Ring of stone
Dragon hasta
Dragonfire shield
Fire cape
You can use any armor you want (Bandos, Third-age melle) but I favor void because of it's accuracy bonus. You can switch anything around, actually, but make sure it's your very best.
Hope this helps at least a bit.