This boss has two separate health bars, one for Lilith and one for the giant baby. The battle ends only when Lilith's health is taken out, but she appears only when the baby's health is down to zero. Lilith comes out only for a short while and will disappear back into the baby. You'll have to repeat the battle against the baby 1-2 more times depending on how fast you can take out Lilith's health.

The baby's entire body can take damage (even the extra red arm on its side), you don't have to focus/be fixated on his head. He disappears/reappears regularly, so you'll have to move around after him. Generally he's not threatening; the only threat there can be is the player's impatience. >_>; Always keep a sharp eye for his attacks and evade them in time. You can always damage him at every other opportunity.

Arbiter does the most damage from what I've tested, but Rebellion is the fastest (good for pausing to evade in time). Aquila's Caliber is handy for closing in. Note that Kablooey's darts and Revenant's Charged Shot are useless for as long as the baby's 3rd eye is closed.

Shockwave:
The baby will pound on the floor and send a shockwave across the floor. Jump over the wave to avoid. During the 2nd/3rd round of the baby battle, he will send multiple shockwaves in a row.

Arm sweep:
The baby does this when you're close to him. Half the time he does it right after a shockwave pound with his thick left arm, and the other half with his thin right arm. Note that the 'hit box' of this move is awkward - even if the baby's sweeping his arm to the left, standing to the right of his arm will still damage you. As long as you're physically close to the sweeping arm it counts as a hit, so be sure to evade in time/keep away. Also, angel/demon evade is safer than jumping against this.

Disco ball:
The baby rarely does this but when he does, it's typically when he has less than 30% health. He'll grab a disco ball out of thin air and throw it at you. This move is awesome - you can easily deflect it by doing a Stinger with Rebellion. Timing is not really required as long as you do it in time right after hearing this sharp noise (indication of this disco ball attack). Do this successfully and the baby will reveal his 3rd eye (but he takes no damage just yet), which you can angel lift over to and whack his eye for massive damage…!

If you fail the deflection, the ball will hit you but the damage is so pathetic there's nothing to worry about.

Last updated: 16 Feb 2013