Piercioueo!

1-Piercioueo! [Pee-Yur-Chee-uo]
2-Cast at the spell which is visible and is been shot at you
3-The wand releases a pointy but white beam.
4-The pointy white beam is capable of piercing through spells casted at the victim and divide them & break down into two pieces both with 1/2 of the natural amount of the original spell , Basically , Some guy casted stupefy at you , and you cast Piercioueo on the stupefy , the stupefy would be pierced into two halves going into different directions , which would OBVIOUSLY NOT be YOU.
The Piercioueo spell can even pierce it's way through megeros spells , or phanta ones , which are definitely a pain when it comes to defending!
PS : Don't combine it with any additional Spell , like "Megeros Piercioueo!" , as it works fine without it , and if you do so , it'll explode as soon as it's casted.
It cannot pierce through Cruciatus curse , Killing Curse , or Impervious Curse , but if it comes in contact with either of them , it can cause a really big explosion , which can surely evade a death , and causes less pain then the cruciatus curse.
5-Was just thinking , some stuff related to dividing stuff into two halves , and this came to my head!

Umm , Could it be rated please? :)

Purely Rejected!

You cannot create a spell that is like you said 'A Pain when it comes to defense' or either a method of defense must be mentioned by you

Mmk , I made it so that it'd be easier to defend against the additional spells , megeros or phanta