The following are known Action Replay Codes for Holy Magic Century on Nintendo 64 (N64).

Device Compatibility: Action Replay & GameShark

Set Defence to 999
8107C236 03E7

Set Agility to 999
8107C234 03E7

Makes your HP 999/999
8107C22C 03E7
8107C22E 03E7

Makes your MP 999/999
8107C230 03E7
8107C232 03E7