Source: EU Portal
This Top of the Tree special puts you on the path of formidable German tank destroyers all the way to the intimidating 
X 
Grille 15 . The branch ranges from fragile but deadly mid-range supports to mobile snipers with formidable firepower at the top! Leave crushed enemies in your wake and advance all the way to the top to reach this gallant German destroyer.
Let’s not beat about the bush—the gun stats on the Grille 15 are extraordinary. The 63 caliber long, 150 mm gun can penetrate 279 mm of armor and will leave enemies wondering what hit them.
It’s stealthy too! Unleash havoc with penetrating rounds and then make the most of its good mobility and sneakiness to relocate. Just make sure to protect your fragile armor and avoid the hostile front line. Hang back from the heat of battle, find a strategic position, and start sniping.
Blast your way up the Tech Tree branch from March 20 at 06:00 CET (UTC+1) through April 20 at 07:00 CEST (UTC+2) and take advantage of great discounts and missions all the way to the top. Don’t forget that you can also purchase an extra boost if you want to speed things up with the 
XP bonuses!
Missions up to Tier X
Available from March 20 at 06:00 CET through April 20 at 07:00 CEST (UTC+2)
You’ll have something to fight for every day for a month! This includes XP per vehicle every day, Crew XP bonuses, and other significant rewards to help you reach Tier X. You can find more information about the missions below:
Crew XP
Reward:
x2 Crew XP
Objective:
- Play a battle
- Place among the top 7 on your team by base XP earned
Restrictions:
- Only in Random and Stronghold Battles
- Only available for the vehicles featured in this special
Damaging Push
Rewards:
6,500 XP
1 Personal Reserve: +50% to Combat XP for 1 hour
Objective:
- Deal 20,000 damage over any number of battles
Restrictions:
- Only in Random and Stronghold Battles
- Only in the following vehicles:
- Can be completed 10 times per account
- The XP will be credited to the vehicle you complete the mission with
Push Through!
Rewards:
- 20,000 XP
Objective:
- Deal 200,000 damage over any number of battles
Restrictions:
- Only in Random and Stronghold Battles
- Only in the following vehicles:
- Once per account
- The XP will be credited to the vehicle you complete the mission with
Grille 15
Rewards:
1 Large Repair Kit
1 Large First Aid Kit
1 Automatic Fire Extinguisher- 1 Personal Reserve: +300% to Crew XP for 1 hour
Objective:
- Play 5 battles
- Place among the top 10 on your team by base XP earned
Restrictions:
- Only in Random and Stronghold Battles
- Repeatable
- Only available for the X Grille 15
In current broken game, grille is a sniper with parkinson..
Ahh the tank no-one ever asked or paid for, but got anyway.
I paid over $150 for this, well… I paid for the WFTE100 initially, then got this hot piece of garbage.
Yes, WG robbed us of our WTE 100….
Grille 15 is utter piece of scrap
Just look forward how WG will screw your over again