Hello guys , all you have to do is to edit what is red and run it in world DB.

Code:
INSERT INTO `creature_template` (`entry`, `difficulty_entry_1`, `difficulty_entry_2`, `difficulty_entry_3`, `KillCredit1`, `KillCredit2`, `modelid1`, `modelid2`, `modelid3`, `modelid4`, `name`, `subname`, `IconName`, `gossip_menu_id`, `minlevel`, `maxlevel`, `exp`, `faction_A`, `faction_H`, `npcflag`, `speed_walk`, `speed_run`, `scale`, `rank`, `mindmg`, `maxdmg`, `dmgschool`, `attackpower`, `dmg_multiplier`, `baseattacktime`, `rangeattacktime`, `unit_class`, `unit_flags`, `dynamicflags`, `family`, `trainer_type`, `trainer_spell`, `trainer_class`, `trainer_race`, `minrangedmg`, `maxrangedmg`, `rangedattackpower`, `type`, `type_flags`, `lootid`, `pickpocketloot`, `skinloot`, `resistance1`, `resistance2`, `resistance3`, `resistance4`, `resistance5`, `resistance6`, `spell1`, `spell2`, `spell3`, `spell4`, `spell5`, `spell6`, `spell7`, `spell8`, `PetSpellDataId`, `VehicleId`, `mingold`, `maxgold`, `AIName`, `MovementType`, `InhabitType`, `Health_mod`, `Mana_mod`, `Armor_mod`, `RacialLeader`, `questItem1`, `questItem2`, `questItem3`, `questItem4`, `questItem5`, `questItem6`, `movementId`, `RegenHealth`, `equipment_id`, `mechanic_immune_mask`, `flags_extra`, `ScriptName`, `WDBVerified`) VALUES (388000, 0, 0, 0, 0, 0, 21322, 0, 0, 0, 'NAME', 'SUBNAME', NULL, 0, 80, 80, 0, 14, 14, 0, 1, 1.14286, 0.4, 2, 8000, 13000, 2, 0, 1, 2500, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 70000, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5000, 5001, 'EventAI', 0, 3, 2900, 100, 15, 0, 0, 0, 0, 0, 0, 0, 100, 1, 70000, 0, 0, 'boss_attumen', 1);

388000 = entry ,change it with another number if you don't like it.
21322 = Display ID (right now it looks like illidan)
NAME = Name of the boss
SUBNAME = Subname of the boss for example "Stormrage"
2900 = Hp of the boss , remember that 1 = 5432 HP so 2900= 5432HP x 2900
First 70000 = Loot ID (you can add loot to it adding new rows in creature_loot_template with entry 70000)
Second 70000 = The equipment ID ( you can add equipment by adding new rows in creature_equip_template with entry 70000)
Boss_attumen = it's an already done script added in every trinity core repack/compile , you can change it with custom scripts and much more.



› See More: [Trinity SQL DEV Pack] Trinity Boss template