Creeper Lingering Effect

As it is right now, Creepers will explode and leave a lingering effect if it had a potion effect. However, Creepers still take damage from potions causing the lingering effect not to be too deadly. Here's my proposal:

- Creepers will no longer take damage from potion effects, or maybe a tag that allows for potion damage. 
- Creepers will now spawn naturally with negative potion effects, unlike spiders that gain from effects they spawn with. 
- Lingering effects should be slightly larger and last longer.
- Charged Creepers should be granted speed upon being struck by lighting.