It's hard to imagine a sadder situation in the game than getting an allied shell in the side of your vehicle. Fire, destroyed modules, ruined mood. It's accidental most of the time.
A player didn't want to send a shell towards an ally. But sometimes they do it on a purpose that's known only to them. The worst part is that this damages the allies who could be useful in battle.
Team kill is a game mechanic that was a part of World of Tanks for a long time. Its main purpose was to immerse players into the game atmosphere. However, with time, negative sides of this mechanic became apparent, like the domino effect, when allies start exchange fire with each other. It resulted in bans and fines, but the game is not about that.
To make gameplay more comfortable we decided to rework the damage system by removing team damage by shooting or ramming.
Remember how frustrating it was to drive your light tank into a heavy and get damaged? Now it's impossible even if an ally decides to purposefully ram you during the battle. Another typical situation that usually ended up with a duel is an ally driving into your reticle during your shot. All the damage went into an unlucky ally that drove forward at a wrong time instead of that TD in those bushes. It won't happen anymore.
If you hit an ally, you will only scratch their paint with a non-penetration or ricochet mark. You will be able to recognize friendly fire with an alternative sound and visuals that are different from the effects from enemy shells.
What About the Artillery?
Getting under a rain of allied arty fire is very unpleasant. With the new mechanics, SPGs won't be able to damage their allies but they will still have a chance to stun them. If we removed any effect on allies from artillery, they would be able to just send shell after shell into a bunch of allies and enemies unpunished while affecting the battle in a major way. The ability to damage an allied SPG by sticking your gun into theirs was removed completely. Now, if an HE shell meets an allied vehicle's gun, it will just go right through.
Is it Now Impossible to Destroy an Ally?
You can still get a blue nickname in the game but it's a worst case scenario. For example if you push an ally from a cliff which damages or destroys their vehicle, be it on purpose or not. The same goes for flipping an ally upside down. Artillery will also get a team killer status if they stun allies all the time.
The player who gets a team killer status loses their friendly fire protection. Their teammates will be able to destroy their vehicle without any penalty. However, don't forget that destroying a teammate weakens your team.