Abyss Mode

Abyss Mode is one of the two new modes featured in the handheld versions of BlazBlue: Continuum Shift II and in the console versions of BlazBlue: Continuum Shift Extend.

In-game description
"Defeat waves of enemies, strengthening your character along the way. Reach the bottom level of Kagutsuchi."

Special mechanics

 * 1) Shop: Here the player uses his accumulated money earned from playing other modes (or Abyss Mode) to buy status boosts or special abilities for his/her chosen character. Items are either unlocked by finding them in Abyss Mode or by increasing the player level. Each item can only be bought once per Abyss Mode playthrough, and are not permanent. When the player loses, the Shop will be reset and items may be bought again.
 * 2) Depth: While fighting enemies in this mode, a "depth counter" will steadily increase, depending on the number of successful hits. This includes Astral Heats. On most occasions, Depth will increase every two successful hits, except during Astral Heats that have extreme combo lengths, such as Makoto's or Litchi's. After a given depth, players will encounter "boss characters". Depth may not be accumulated during a Boss Fight.
 * 3) "Boss characters": These characters have special status levels, and only appear at predetermined levels. They appear at Depth Levels 30, 60, every 100 Depths, Depth 999, and the special Ragna the Bloodedge boss at Depth 666. Special statistics vary between the bosses. Early on, the bosses will be buffed-up versions (by way of status levels) of the standard characters, but later on, the player may also encounter strengthened Unlimited characters. After defeating a boss, the player can choose one reward out of five from a list. These are always randomly chosen, but can consist of status boosts, Reward boosts, Special abilities and positive (skip a certain number of floors) or negative (go back a certain number of floors) Depth boosts.
 * 4) Reward: After defeating enemies, the player recieves a Reward. The total Reward can be seen in the upper left corner, above the player's HP gauge (where normally the points in Score Attack/Arcade would be shown) and in the upper right corner every 100 floors on the Abyss Menu screen, where the player can decide whether to go forward or leave the Abyss. The Reward added to the total after defeating an enemy depends on the Depth the player is at. However, keep in mind that if you lose a battle, you leave the Abyss empty-handed. The Reward you accumulated until your loss will drop to the next 100th Depth. For example, if you were to lose on floor 236, your Reward is dropped on floor 300, and you will have to defeat the boss there to reclaim it. Your reward will also stay on floor 300 if you were to lose to the boss there, as you never got past that point. One other thing to remember is that if you tried to reclaim your last loss and lose on the way there, your old loss will be gone forever and the new loss will be assigned to its position (e.g. you have a loss to be reclaimed at floor 300, but lose on floor 150. The loss at floor 300 is erased and the new loss can be found at floor 200). You can still recieve the reward and EXP for playing Abyss Mode, as the two items are seperate.

Status levels
Players can equally strengthen their own character to be able to match up with stronger bosses during the course of Abyss Mode. These boosts are listed in four categories. The maximum level of each category is 50. Above that, no more status boosts are accounted for. With level 50 on every status, your character has You can buy initial Status levels in the Shop at the beginning. Those boosts range from +1 to +9. If you were to buy all of them, you could potentially start with Level 45 on all stats. After defeating a boss, you could also get single Status boosts or, albeit rare, a boost to all stats (called "All +1" or "All +2"). This makes for faster level gain on all stats.
 * StrLv: Short for Strength Level. Boosts in this category give more attack power to your character's attacks.
 * DefLv: Short for Defense Level. Boosts in this category give more health to your character.
 * HetLv: Short for Heat Level. Boosts in this category give more Heat to your character at the start of a fight. (This also effects how much Heat you gain from your attacks. Confirmed.)
 * SpdLv: Short for Speed Level. Boosts in this category increase the overall movement speed (walking, dashing, Air Dashing) of your character.
 * twice as much HP,
 * doubled damage,
 * a Heat stat of 100 at the start of a round and
 * doubled speed.

Special abilities
Special abilities come in various forms. They can give another Break Burst Symbol, reduce the Heat consumption for Rapid Cancels to 25% etc. Not all of them are unlocked by player level progress, some of them have to be won from specific bosses.

Only three Special abilities can be active at a time. When a new Special Ability is selected, the top one will be erased and the new one is placed at the bottom. That said, you are better off choosing your abilities wisely, only switching out when truly necessary.

List of Special abilities
Here, all available Special abilities form Abyss Mode will be listed, along with unlock conditions, their in-game description and their prize in the shop.

Note: Some of them will unlock with rising player level. This is NOT listed here. Instead, it is very well advised you raised your player level to 20 before tackling Abyss Mode in full.
 * Auto Heal: Hit points will be restored over a given period of time. (Cost: 1000)
 * First Aid: The amount of HP regenerated after each battle will increase. (Cost: 1000)
 * Blood Sucker: Upon landing an attack on an enemy, enemy hit points will be absorbed. (Unlock by beating the boss on Floor 666. Cost: 5000)
 * Heat Recovery: Heat will automatically be restored over a given period of time. (Cost: 1000)
 * Quarter Rapid: Rapid Cancels can be performed using only 25% Heat. (Cost: 1500)
 * Heat Keeper: Abilities now consume 50% less Heat than before. (Cost: 4500)
 * Human Fortress: Guard Primers will no longer be consumed. (Cost: 2000)
 * Free Barrier: The Barrier Gauge will no longer diminish. (Cost: 3500)
 * Extra Burst: Break Burst can now be performed twice. (Cost: 2000)
 * Super Burst: Increase the power of the Break Burst. (Cost: 4000)
 * Penetrator: All attacks have a chance to become unblockable. (Cost: 2500)
 * Armor Grinder: Chip damage has been increased. (Cost: 2500)
 * Lucky Puncher: Attacks have a chance to deal extra damage. (Cost: 3000)
 * Revenger: Damage increases significantly when remaining HP is low. (Cost: 3000)
 * Balance Breaker: All attacks have a small chance to instantly defeat your enemy. (Cost: 4000)
 * Berserker: Damage increases significantly, but at the cost of HP over time. (Cost: 4500)
 * Counter Puncher: All Counter Hits are now Fatal Counters. (Cost: 1500)
 * Absolute Field: Lower opponent's combative abilities. However, this will cost a percentage of your reward. (Cost: 5000)
 * Maze Walker: The rate at which you go deeper increases. (Cost: 3500)
 * Red: Your character will be surrounded by a red aura. (Cost: 100)
 * Black: Your character will be surrounded by a black aura. (Cost: 100)
 * Silver: Your character will be surrounded by a silver aura. (Cost: 100)
 * Gold: Your character will be surrounded by a gold aura. (Cost: 100)
 * Rainbow: Your character will be surrounded by a colorful aura. (Cost: 3500)
 * Turn Unlimited: Your character will unleash their true potential, becoming unlimited. (Cost: 10000)

Achievements related to Abyss Mode
There are 9 achievements related to Abyss Mode, out of 73 total.
 * Welcome to the Abyss Hole: Defeated the boss on Depth 100.
 * We Have To Go Deeper: Defeated the boss on Depth 300. (reference to the Christopher Nolan movie Inception)
 * That's Deep, Man: Defeated the boss on Depth 500.
 * Gotterdammerung: Defeated Ragna, the boss on Depth 666.
 * Seek a Way Out!: Defeated the boss on Depth 999. (a reference to the visual novel Nine Hours, Nine Persons, Nine Doors)
 * All You Need Is Love: Did not buy any items when starting the game.
 * ...And I'm All Out of Bubblegum: Do not buy any starting items and defeat the boss on Depth 999.
 * If It Bleeds, We Can Kill It.: Defeat the boss on Depth 999 without learning any special abilities.
 * Your Clothes, Give Them to Me: Obtained all of the items from the shop.