no invincibility is not creative requires 1.6 OK ill tell you the secret

1.type /give (player) 137

2.place the command block and type in effect @p 22 9999 100

3.get diamond armor enchant them like this helmet:projectile protection and respiration chest plate:blast protection and aqua affinity leggings:fire protection and thorns boots:protection and feather falling
or you can just put them all on each one

4.put in your inventory 4 stacks of 64 enchanted golden apples

5.enchant on a diamond sword:smite,knock back,fire aspect,unbreaking,looting,efficiency,power,punch,flame and infinity

6.enchant on a bow:unbreaking,looting,fire aspect,flame,infinity and efficiency and also just take one arrow and enchant it with efficiency and unbreaking

7.have lots of potions in inventory e,g, splash potion of poison or potion of night vision

8.carry a pumpkin around in case of endermen put it on

9.carry full set of diamond tools with all tool enchantments for all of them

10.ride on a unicorn with diamond armor enchanted with:fire protection and feather falling

if i have missed anything very powerful then please say something in the comments and enjoy being invincible:)

11.(optional) if your fighting a blaze or anything related like magma cube use a normal diamond sword and normal bow