MYTHICMOBSINTERNALNAME_2:
  same_as: MYTHICMOBSINTERNALNAME
MYTHICMOBSINTERNALNAME:
  USE:
    FORMULA: true
    LIMITED_XP: false
    COMMAND: true
    LEVEL_END: true
  CONDITIONS:
    CONDITION1: '%mmocore_level%;>=;5;NUMBER' #you can check by >=, >, <=, <
    CONDITION2: '%mmocore_is_casting%;==;true;BOOLEAN' #only ==
    CONDITION3: '%mmocore_class%;==;KNIGHT;STRING' #only ==
    WARRIOR_CLASS: '%mmocore_class%;==;Warrior;STRING' # only ==
    MAGE_CLASS: '%mmocore_class%;==;Mage;STRING' # only ==
    BOOSTER2: '%player_has_permission_booster.2%;==;yes;STRING' # Booster x2
    BOOSTER5: '%player_has_permission_booster.5%;==;yes;STRING' # Booster x5
    BOOSTER10: '%player_has_permission_booster.10%;==;yes;STRING' # Booster x10
    CHECK_BOOSTER_2_5: '#BOOSTER2#;#BOOSTER5#;false;COMPARE_CONDITIONS' # #CONDITION_1#;#CONDITION_2#;#CONDITION_3#;COMPARE_CONDITIONS
    CHECK_BOOSTER_2_10: '#BOOSTER2#;#BOOSTER10#;false;COMPARE_CONDITIONS' # COMPARE_CONDITIONS condition checks if 3 conditions have same values: true true true, false false false
    CHECK_BOOSTER: '#CHECK_BOOSTER_2_5#;#CHECK_BOOSTER_2_10#;true;COMPARE_CONDITIONS' # #CONDITION_3# can use in CONDITION use use true/false (rcm use true/false for check)
  CUSTOM_FORMULA:
    NORMAL: '%mob_xp%'
    BOOSTER2: '%mob_xp% * 2'
    BOOSTER5: '%mob_xp% * 5'
    BOOSTER10: '%mob_xp% * 10'
  COMMAND:
    OUT_OF_BOUNDS:
      - '#WARRIOR_CLASS#;mi give MATERIAL FRAGMENTS %player_name% 3 0 100 0 s;1' # If player is class warrior, system will give 3 material (Chance = 1%)
      - '#MAGE_CLASS#;mi give MATERIAL FRAGMENTS %player_name% 1 0 100 0 s;1' # If player is class mage, system will give 1 material (Chance = 1%)
    WITHIN_LIMITS:
      - '#WARRIOR_CLASS#;mi give MATERIAL FRAGMENTS %player_name% 3 0 100 0 s;30' # If player is class warrior, system will give 3 material (Chance = 30%)
      - '#MAGE_CLASS#;mi give MATERIAL FRAGMENTS %player_name% 1 0 100 0 s;30' # If player is class mage, system will give 1 material (Chance = 30%)
  FORMULA:
    OUT_OF_BOUNDS:
      LOWER:
        - '%mob_xp%'
      HIGHER:
        - '0'
    WITHIN_LIMITS: # If a player has booster x2 and x5, player will receive 7 xp | x2 x10 -> 12 xp | x5 x10 -> 15 xp | x2 x5 x10 -> 17 xp
      - '#CHECK_BOOSTER#;%mob_xp%;0' # If a player doesn't have any booster, player will receive 1 xp when kill mob -> If a player has any booster, mob gives 0 xp
      - '#BOOSTER2#;#cf_BOOSTER2#;0' # If a player has booster x2, player will receive 2 xp when kill mob
      - '#BOOSTER5#;#cf_BOOSTER5#;0' # If a player has booster x5, player will receive 5 xp when kill mob
      - '#BOOSTER10#;#cf_BOOSTER10#;0' # If a player has booster x10, player will receive 10 xp when kill mob
  XP:
    DEFAULT: 1
    MAX: 1
  LEVEL:
    END: 10
    MAX: 5
    MIN: 1
 

Then use luckperm add permission to player for a short-time:
/lp user <name> permission settemp booster.2 true 5m
  -> x2 booster, 5 minutes
/lp user <name> permission settemp booster.5 true 5m
  -> x5 booster, 5 minutes
/lp user <name> permission settemp booster.10 true 5m
  -> x10 booster, 5 minutes