Minecraft Giant summoning

/scoreboard objectives add RNG dummy
/team add checked

/scoreboard players add @r RNG 1
/scoreboard players set @a[scores={RNG=10..}] RNG 0
/execute as @p if score @s RNG matches ..9 run team join checked @e[type=minecraft:zombie,team=]
/execute as @p if score @s RNG matches 10 run execute as @e[type=minecraft:zombie,team=] at @s if block ~ ~10 ~ air run summon giant ~ ~ ~