Pretty sure they only ilevel sync it so it doesn't become a rofl stomp like doing Immaculate EX in full i500
Well the fight is literally just Shiva EX but rebalanced for the level range that it is. They could easily have adjusted Shiva's HP/damage even higher and made it a i480-485 (or whatever) fight instead and it would have made no difference, other than excluding fresh level 80 players.