In Embodiment of Scarlet Devil, the spellcard bonus is calculated using the following formula (thank you digiversalgalaxy for providing me this):
Spell Card Bonus = Starting Bonus + ((Starting Bonus*Time Remaining)/10)
The Starting Bonus is as follows (thank you zero318 for the following table):
This may look a bit confusing at first, but it’s actually very simple. There are 64 values in the table and 64 spellcards in the game. So if you rearrange the information a bit you end up with:
200000 - spells 1-7
250000 - spells 8-14
300000 - spells 15-32
400000 - spells 33-40
500000 - spells 41-46
600000 - spells 47-51
700000 - spells 52-64
The spell number can be found in the game:
So let’s take Rumia’s midboss spellcard from Hard and two of Remilia’s spellcards (Normal & Lunatic).
Spell Card Bonus = 200000 + ((200000*14)/10) = 480000
Spell Card Bonus = 200000 + ((200000*6)/10) = 320000
Spell Card Bonus = 500000 + ((500000*25)/10) = 1750000
Spell Card Bonus = 600000 + ((600000*23)/10) = 1980000
Since many spellcards share the same spellcard number even if they are on different difficulties, you will get the same bonus if you capture it on the same second (left side gif is from Easy, while right side gif is from Lunatic). Also, for reference, I already compared how spellcards with same number look like on different difficulties: touhou-memories.com/eosd spellcards. Please check that out if you are interested.
For spellcards that can have the remaining time higher than 99 seconds, the real value won’t be displayed on screen, but the spellcard bonus will take into account the real value. We can calculate which was the actual value of the remaining seconds (one of the replays from ux.getuploader.com/darathreplays was used for making this gif).
6960000 = 600000 + ((600000*x)/10)
⇒ x = 106 seconds left