[section=Notes] Mainly for use in 10TM Casual because of limited SP, limited attack options, and boss action speed. That being said, some of these points are general and can apply to any category and difficulty.

[section=Regarding Damage Fall Off] Repetitive use of Up Drill, Down Drill, or Air Dash results in decreased damage. This damage fall off will occur regardless of if you hit an enemy or not. As such, even using Air Dash for movement will decrease its damage. Amulets DO NOT reset fall off damage. Cutscenes also DO NOT reset fall off damage. Reloading the game WILL reset any damage fall off. Because every boss has an auto-save right before starting the fight, it is a good habit to reload the game before every boss fight after obtaining Air Dash. Reloading to reset damage fall off can more than DOUBLE the amount of damage it would've inflicted if you hadn't reloaded.

[section=Regarding Shielding] After finishing certain strings of attacks, a boss will be in a flashing yellow state. This is known as having Shielding. The duration of Shielding varies depending on which attacks induced it. Attempting to attack a boss during this state will generally result in no damage and no hitstun. That being said, the Up Drill and Down Drill hits through Shielding and inflicts both damage and hitstun. Despite this ability to hit through Shielding, remember that drills are prone to damage fall off. As such, this can lead to drills dealing 0 damage but still inducing hitstun (which of course is very slow). When a boss is attacking, they are more prone to gain Shielding, but the Shielding also lasts for a shorter period of time. As such, when a boss has Shielding or is performing an attack, it is recommended to revert to repeated 3-hit combos as opposed to Penta combos.

[section=Regarding Quick Reflexes] After inflicting a certain amount of damage to a boss, they will gain a buff called Quick Reflexes. While having Quick Reflexes, bosses can escape combos and generally cannot be hitstunned. Using Amulet will remove Quick Reflexes, which can be useful to extend combos and defeat bosses before they can perform attacks.

[section=Regarding Stamina] Stamina Points (SP) is the limiting metric in which actions can be performed by Erina. The amount of SP consumed varies depending on the action. Jumping of any kind does not consume any SP. While SP slowly refills over time, emptying the SP meter will cause SP to refill twice as fast as it normally does. As a result, during boss fights, it is almost always optimal to empty the SP meter when performing a string of attacks in order to force the meter to refill quickly, which allows for more attacks.

[section=Optimizing Combos] A Penta Combo (the grounded 4-hit combo into a grounded spinning drill) drains almost all of your SP meter (but leaves a little left). There are a few options to empty your SP meter after the Penta Combo. Here are the important ones:

     1. Up Drill      2. Nothing (drain SP by performing an attack that does not hit the boss)      3. Air Dash      4. Wait (to restore SP)

For most new runners who haven't learned boss fights, they typically will perform an Up Drill after the Penta Combo (Penta). In most scenarios, performing an Up Drill is the least optimal option (Note: This strictly applies to Casual). Often times when you perform Penta -> Up Drill, the boss will end up with additional amounts of Shielding, which will prevent you from following up with additional attacks. However, if you perform Penta -> Nothing (you can Up Drill away from the boss or use a Walking Hammer away from the boss to drain SP), the boss will not have additional Shielding, which will allow you to combo the boss again. Similarly, once you obtain Air Dash (AD), you can perform Penta -> AD. Air Dash also does not have additional Shielding, which will again allow you to combo the boss again. To summarize, these are the general results you can obtain when fighting bosses:

     1. Penta -> Up Drill      2. Penta -> Nothing -> Penta -> Nothing/Up Drill      3. Penta -> AD -> Penta -> AD/Up Drill      4. Penta -> Wait -> Down Drill -> Up Drill      (Note: Using Ribbon's Charged Shots in between sets of combos increases hitstun on bosses allowing for followup.)

As you can see, Up Drill is essentially a combo string closer. In the second and third scenarios, you could theoretically continue these strings even more if it weren't for Quick Reflexes activating (boss depending of course). At this point, you have a few options. You could use Amulet to remove Quick Reflexes and extend your combo, or you could end your combo with an Up Drill. In the fourth scenario, you can wait to restore your SP after the Penta then perform Down Drill -> Up Drill as opposed the the standard fair of Penta -> Up Drill. As such, it is almost always suboptimal to immediately perform an Up Drill right after a Penta combo. Of course, Penta -> Up Drill does have a unique property: it is a "True Combo". Unlike the other combos, Penta -> Up Drill will lock the boss and almost always guarantee the combo without issues. Ending the combo with the alternatives methods above may give bosses enough time to escape. For some bosses with high priority, such as Rita or Kotri, they can escape and perform their Cut-In attack. Once you have no real options remaining, and a boss has gained extended amounts of Shielding, it is best to start performing Down Drills and Up Drills, which can attack through Shielding.

Regarding using Amulet to extend a combo through Quick Reflexes, using Amulet will set your SP to a fixed amount. This amount of SP generally only allows you to perform a 3-Hit combo at most. As such, after immediately using an Amulet, you can use Boost, which will increase the speed that your SP refills, which will ultimately allow you enough SP to perform a full combo. The act of performing a Boost immediately after Amulet is commonly called "AmuBoost".