HOWEVER!
1. Notice that the glitch had no resistance whatsoever in non-elemental attacks. Max out these skills. Lucky star, Star Shower(Natalie), Arrow Rain and Combo shot(Anna) should be enough.
2. Defense & Magic Defense or Resistances doesn't matter(it kills you with one hit anyway), just equip some Equipments that boosts Attack and/or Magic attack.
3. Get Morale status which prevents the party members from dying after one hit. Kitten Fort summon should be enough.
4.Enter the battle, use a(non elemental) multiple-target skill, a strong one target(again, non elemental) skill, and use summon kitten fort.
5.Heal if necessary. Repeat these steps and there you go! It's not really hard in any difficulty(even in epic), as long as you know what to do.
For anyone having trouble for the glitch boss(SPOILER!):
The Glitch can be encountered in the Waste Disposal Plant area, you need to activate the II, III, VI, IX and X switches and deactivate the rest in order to get there. You also need 1 Cooper Key and 1 Silver Key. Use those keys to open the locks, approach the treasure chest on the upper corner and before you know it, you encountered the glitch
Problems:
1. Can summon 2 Babies each turn
2. The glitch only has 1 attack: Instantly kills 1 party member.
3. The Glitch absorbs ALL kinds of elemental attacks.
4. The Glitch is immune to ALL debuffs.
5. Can't Escape.
Got all upgrades, and I found a faster way to receive gifts rather than keep using the slot machine.
First, make sure you completed all the levels and have a lot of mines, bombs and nukes. Go to the last level, and either:
1.Use 3 mines and then a nuke, or
2.Use a nuke and then some bombs to free the santa
By doing so, you should receive a total of 237 gifts.
Repeat this strategy, and if you are short on powerups, you can always rely on the slot machine(make sure your luck upgrade is maximum). Have a nice holiday! :)
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