Spell Combos

Spell Combos refer to a mechanic in Magic where firing the same, or even more so different spells in rapid consecutive order will start building up an additional penalty to the Mental Power required to cast each spell, which can stack to a large amount. This depends on the magic user's Mental Endurance, and someone with high endurance can cast more consecutive spells before starting to stack up this penalty.

Starting combos
A combo is started when the user does not give their chance for their mind to "cool down" after a spell. Upon the second time casting a spell within a short amount of time after the first has ending, a combo is started - generally within 4 seconds.

Ending combos
A combo ends when the user successfully disengages (intentionally due to waiting or unintentionally due to being too slow), such that they are not casting any magic for 4 seconds.

Combos can also be interrupted by running out of Mental Energy, such that the magic user is forced to wait until it is replenished from their Mental Reserve.

Personal combo limit
Depending on Mental Endurance, magic users can only use a specific amount of Mental Energy before they start to accumulate a penalty to any further spells in the combo. This penalty continues stacking, making it inefficient to continue casting spells beyond their personal combo limit.

It is possible for magic users to determine what their combo limit when they start feeling that they are getting mixed up or finding spells unusually more difficult to cast.

Increasing power
When going towards the personal combo limit, the power of the next spell increases, even beyond the combo limit. For example using arbitrary numbers, if 50 / 100 MP from the combo limit is used, the next spell will have a 150% of its original power. If at 200 / 100 MP (twice above the combo limit), the next spell will have 300% of its original power.

To the magic user, this feels like as if they are getting "in the zone", and they can tell when they have reached their combo limit, although staying "in the zone" for too long will cause the stacking penalty to eventually force them to terminate the combo.

This quirk of spell combos can lead to some interesting strategies, such using several low-grade spells to reach 200% spell power, and then unleashing a surprise spell with twice the usual power.

Spell Combos are a matter of priorities
Magic users have to prioritize either Using a lot of magic in a short amount of time or Keeping spell cost low.

If it is more important to, for example, finish a weak opponent off, it might be worth suffering the stacking penalty and keeping on going with the combo. This can lead to dealing an enormous amount of damage at the cost of being extremely wasteful with mental energy.

However, if it is more important to survive as long as possible without going into Mental Incapacitation, it is more important to only carry out spell combos and disengaging the combo when the user feels like they're at the limit.

Switching between different spells in a combo increases power gain by x2
While this requires a good Mental Flow to avoid extra mental energy due to switching Spell Focus, alternating between casting Ice Spike and Fireball would be more efficient than simply repeating Ice Spike over and over - this is because for every spell that is unique to the combo, the power increase by that spell is doubled. See Example 2 as a demonstration of this.

Examples using arbitrary numbers
The following are some examples of how the cost and power of certain spells get modified during spell combos. The numbers are all arbitrary and used for the explanation, and do not reflect real values.

Example 1: x5 Ice Spike + 1 Teleport
Magic user's combo limit: 100MP Total cost if spells were not casted in a combo: 350MP (used 164% more than normal)

* Since the user has a 100% efficiency spell combo limit of 100MP, after having used 50+50 MP for the first two ice spikes, they will start gaining a penalty each consecutive spell that increases by 25% each time. If the user mastered the mechanics of Ice Spike such that it only costs 10MP for them, they will be able to cast 10 ice spikes until they start approaching their spell combo limit

** By casting the teleport spell at the very end, the user's cost for teleport is doubled - however, they also get the advantage that since their mind is "in the zone", they are able to teleport x2.25 times the distance that they could normally teleport if they had used teleport first.

*** The third Ice Spike was fired when the user had built up 100 MP of combo - having built that much is exactly the magic user's limit. However, they don't incur a penalty for firing the last spell at their limit - the following spells start taking the penalties from the limit.

Example 2: Ice Spike, Fireball, Ice Spike, Fireball, Fireball
Magic user's combo limit: 100MP

Magic user's switch speed: 2 seconds Total cost if spells were not casted in a combo: 250MP (used 165% more than normal - this also takes into account the penalty accrued from trying to cast the Fireball at order 4 prematurely)

* Due to the magic user having switched from Ice Spike to Fireball, the power of the second fireball went up to 150% instead of 125%. If the user had just casted two ice spikes in a row, the second ice spike would have only gone up to 125% of original power instead.

** Since the user has a switch speed of 2 seconds due to their Mental Flow, and that they had fired a Fireball only 1 second after their second Ice Spike, they incur a penalty of 100% of the normal cost, in addition to the 50% penalty coming from the combo that has gone over their limit of 100MP.