You know, this thing.
This would be an item that, when used, causes the player to rapidly change colors (possible without breaking the game?) and sparkle for about 10 seconds. During this time, they are completely unaffected by any form of damage, including negative AddHealth events and Kill events. Also while invincible, touching a non-invincible enemy player will cause them to die.
Alternatively, if not an item, it could be a projectile for spawning with events. As a projectile, it would bounce around, never losing momentum. If someone "collects" it (the projectile hits them) they become invincible. Otherwise, it would disappear after about half a minute.
