How do spells decide which intro to play?

The spell index determines which intro animation is used. It's set up so that it can only choose from 3 intros (black, white/effect, summon) but you could modify it to make different intros for white and effect magic. Here is the subroutine that handles this. I also put the animation pointer table at the bottom. Strangely, they seem to have included the lore intro in this table ($0FB2), though I don't think it ever gets used. Lore, Blitz, SwdTech, and Rage intros are handled elsewhere.

Code:

C1/AB9F: A0 02 00     LDY #$0002
C1/ABA2: 7B           TDC
C1/ABA3: AA           TAX
C1/ABA4: B1 76        LDA ($76),Y     ; attack number
C1/ABA6: C9 18        CMP #$18
C1/ABA8: 90 11        BCC $ABBB       ; branch if black magic (X = 0)
C1/ABAA: E8           INX
C1/ABAB: E8           INX
C1/ABAC: C9 36        CMP #$36
C1/ABAE: 90 0B        BCC $ABBB       ; branch if white or effect magic (X = 2)
C1/ABB0: E8           INX
C1/ABB1: E8           INX
C1/ABB2: C9 51        CMP #$51
C1/ABB4: 90 05        BCC $ABBB       ; branch if esper (X = 4)
C1/ABB6: 9C C0 62     STZ $62C0       ; don't ignore block graphics
C1/ABB9: 80 2C        BRA $ABE7
C1/ABBB: EE C0 62     INC $62C0       ; ignore block graphics
C1/ABBE: C2 20        REP #$20
C1/ABC0: BF 8E 91 C1  LDA $C1918E,X   ; +$1E = pointer to pre-attack animation data (+$D07FB2)
C1/ABC4: 85 1E        STA $1E
C1/ABC6: 7B           TDC
C1/ABC7: E2 20        SEP #$20
C1/ABC9: 20 B3 9C     JSR $9CB3       ; init battle animation data
C1/ABCC: 20 5B AC     JSR $AC5B       ; execute battle animation
C1/ABCF: 20 89 BC     JSR $BC89       ; get attacker number
C1/ABD2: A5 10        LDA $10
C1/ABD4: 30 0B        BMI $ABE1       ; branch if monster
C1/ABD6: 29 03        AND #$03
C1/ABD8: AA           TAX
C1/ABD9: AD A4 62     LDA $62A4       ;
C1/ABDC: D0 03        BNE $ABE1
C1/ABDE: FE AE 61     INC $61AE,X
C1/ABE1: 9C C0 62     STZ $62C0       ; don't ignore block graphics
C1/ABE4: 20 43 AB     JSR $AB43       ; init single thread animation
C1/ABE7: 20 8B AB     JSR $AB8B       ; reset attacker graphical action
C1/ABEA: 60           RTS

; pointers to pre-attack animation data (black magic, white/effect magic, esper, lore, +$D07FB2)
C1/918E:              .DW $0F88, $0F96, $0FA4, $0FB2