Wall of Ice, Lateral (1) [Create a bone-chilling barrier of ice.]
Wall of Ice, Vertical (1) [Create a bone-chilling barrier of ice.]
Frostball, Spear [Launch a ball of ice.]
Carve, 1 Row [Attack with a sword.]
The boss opens with Wall of Ice. It will then use Frostball, move, change weapon to Sword and charge up to use Carve. Carve can deal 1500 damage against a Bow target. It will then switch back to Staff and use Wall of Ice again, repeating its pattern. Avoid standing in the ice wall as it hurts. Starting at 50%, he will occasionally call for Defense Amps as reinforcements.
Prior to 26-10, 54B2 will flee on his turn unless other enemies are present on the board.
In 26-10, he will not flee when alone, but does when you reduce him below 75% HP. He uses Royal Blade every turn unless charging up, so you are safe attacking him vertically. When he charges, move your squad away from his horizontal/vertical since he will use Grand Cross next. 54B2 may summon additional enemies: 3 Sword units or 2 Electrosappers.
Mechabird clones itself into multiple units, each with high HP and ranged darkness attacks. Kill the original Mechabird to end the fight. Unlike the boss, the clones of Mechabird are 100% vulnerable to confusion.
There are two Nebulators positioned so that when their turn arrives, they both use Dark Matter, 3 Columns, dealing massive Darkness damage to all your units. They start with a counter of 2, so you have 2 turns to nuke one of them to create a safe zone. They will charge up before using Dark Matter Breath, but then use it consecutively without charging once alone.
Teleport moves all your units to one half of the screen and inflicts damage. The enemies in the corners use Teleport without the damage on the three spaces around them. Keep away from the corners and these enemies unless you want to teleport to the other side. Kill the other small mobs doing column attacks before attacking the boss in the middle, as usual. At low health, the boss will use Quake.
Hail of Blows, All [20 Hits. Hammer foes with a merciless barrage of blows.]
Summons 2 tentacles mobs that heal him. Kill them first both at the same time, or they'll respawn and spawn some hitters (same skin, no heal capacity just vertical shoot, multiply). Then focus on him. Avoid the space above and below him as much as possible he uses paralyze a lot. Keep all units to the sides. When low in life (last third maybe), he uses a lot his last ability to hit the whole team, need heal.
Plague, All [4 turns. Inflict multiple status ailments.]
Scythe, 1 Row [Slash using both hands as though wielding a scythe.]
Repel, Area (1) [Knock foes back.]
Vortex, All [Unleash a voracious vortex.]
Plague can cause confusion, poison, and/or sleep to all squad members. Panacea is extremely useful, but it is ideal that the caster also equips Ward skills to prevent themselves from being affected by the status ailments. Kill all the small monsters first, then focus on her. She will counter pincer attacks with Repel, Area (1). Unlike other bosses, Marilith is 400% vulnerable to poison.
Tiamat alternates between ice and fire attacks with the following cycle: attack area 1, attack column, change element type. She comes with two Ice Spawns and two Fire Spawns. Try to kill the monsters first, then attack Tiamat after the area attack from the sides for two turns. Once she changes element type, move everyone away from her area range. Rinse and repeat. Take note that fire and ice attacks can heal her depending on her current element, but will deal extra damage when she is of the opposite element.
Death Ward becomes handy in this battle. Keep as many minions alive as possible as they are susceptible to Death Roulette and can save a squad member from being chosen. Lich can seal physical moves by type, so damage is mainly done by elemental attacks as the battle goes on until Death Roulette chooses Lich and unseals all weapon types.
Power Enhancer buffs a random minion, and it will release either a full row/column cross or area (1) move with a knock back, which can potentially knock units into the boss's line of fire. Second Wind absorbs life from other minions, which is why it's even more important to eliminate them quickly (or have a unit with negate healing).
You start the fight with just the boss. The boss counters all pincers (except in Staff form) with Counterattack; Fancy Footwork is very useful for this. The boss's pattern is Cyclone, summon two minions, and then switch weapon (Sword -> Spear -> Bow -> Staff -> repeat). Depending on its weapon, it may summon AOO (Sword), BOO (Spear), or COO (Bow). It if you attack a minion which has the same weapon type as the boss, the boss will counter with Supporting Fire. In Staff form, the boss will not summon minions, but will charge Quake. Levitate helps to avoid Quake. After it reaches zero health, 6ZOO transforms to its second form. Any minions left will not be destroyed.
6ZOO recovers all health and now is based on element rather than weapon type, and no longer counterattacks. After several rounds, it summons two matching Elemental Spinners, which switch elements with the boss. Black Hole teleports out two allies for two rounds. The boss switches its element type and use its powerful corresponding attacks. When its health is down to approximately 25-30%, it unleashes Terra Panic, which inflicts many status ailments: petrify, confusion, sleep, etc.