Apparition Boss

INIT:/scoreboard objectives add spawn dummy
INIT:/give @p spawn_egg 1 0 {display:{Name:Spawn},EntityTag:{id:Bat,NoAI:1b,Silent:1,ActiveEffects:[{Id:14,Amplifier:0,Duration:2147483647,ShowParticles:0b}]}}
/execute @e[type=Bat,name=Spawn] ~ ~ ~ /scoreboard players add @e[type=Bat,name=Spawn] spawn 1
/execute @e[type=Bat,name=Spawn] ~ ~ ~ /particle portal ~ ~ ~ 0 0 0 1 10
/execute @e[type=Bat,name=Spawn] ~ ~ ~ /execute @e[type=Bat,score_spawn_min=100] ~ ~ ~ /summon Zombie ~ ~ ~
/execute @e[type=Bat,score_spawn_min=100] ~ ~ ~ /playsound minecraft:entity.wither.spawn block @e
/kill @e[type=Bat,score_spawn_min=100]