The Berserker is the tank. This perk relies on getting up close and personal with zeds, which can be pretty dangerous. That is why he is equipped with the Stun Grenade.

XP Objectives:

• Dealing damage with Berserker Weapons
  
• Killing Zeds near another player with a Berserker Weapon

Perk Skills:
Now I will explain the Perk skills, what they do and the best ones to choose.
LEVEL 5 - SURVIVAL

• Dreadnaught: Increase total Health by 75% (This makes your total health 175%)
  
• Skirmisher: Move 20% faster and sprint 25% faster when using a perk melee weapon. Regenerate 2 HP each second. (If your health is at 25 you will go to 27-29 and so on)

RECOMMEND: Skirmish. Because if your on fire or a Bloat vomits on you, you technically will not receive much damage, it's about a 50% reduction.
LEVEL 10 - COMBAT

• Vampire: Heal 4 points of Health for every Zed you kill with Perk Weapons. Attack 20% faster with perk melee weapons.
  
• Butcher: Attack 20% faster and do 25% more damage with melee weapons.

RECOMMEND: Ok, you can do what you want with this Vampire combined with Skirmish can make your health and damage op, but I personally would switch it up with butcher because it balances movement and attack speed.
LEVEL 15 - CLOSE COMBAT

• Resistance: Gain 20% Resistance to all damage. Gain an additional 20% Resistance to Poison and Sonic Damage.
  
• Parry: Parrying with a perk melee weapon reduces incoming damage 40% and increases both melee attack speed by 5% and melee damage by 35% for 10 seconds.

RECOMMEND: Parry. Your going to be parrying a lot anyway right? So this is clearly the best option. But, if you need that resistant to Bloats and Sirens (especially Bloats), go with Resistance.
LEVEL 20 - POWER

• Smash: Hard attacks with perk melee weapons do 50% more damage, do 25% more damage on head hits, and have 200% more stumble power.
  
• Massacre: Light attacks with perk melee weapons do 30% more damage and all attacks with perk melee weapons are 5% faster.

RECOMMEND: Smash. The Crovel becomes a tier 5 weapon with it's blunt attacks. Fleshpounds will be scared by this!
HOWEVER - Those who dislike the Pulverizer because of it's weak light attacks should go with Massacre!
LEVEL 25 - ADVANCED TRAINING

• ZED TIME - Berserker Rage: Heal 25% Health and Zeds close to you try to flee when you enter Zed Time.
  
• ZED TIME - Spartan: During Zed Time, you attack with perk weapons and move in real-time.

RECOMMEND: Spartan. Heal 25% really? 25 PERCENT?!? Yeah Real Time for the win!

Here are some good skill combos for your perk, each are good for different situations!
The Kiting King
You can run but you can't hide...

• 5 - Skirmish
  
• 10 - Butcher
  
• 15 - Parry
  
• 20 - Massacre
  
• 25 - Spartan

The Lawn Mower
Don't give them a chance

• 5 - Skirmish
  
• 10 - Vampire or Butcher
  
• 15 - Resistance
  
• 20 - Smash
  
• 25 - Spartan

The Boogie Man
This one focuses on keeping Zeds away from you and your teammates

• 5 - Skirmish
  
• 10 - Butcher
  
• 15 - Resistance or Parry
  
• 20 - Smash
  
• 25 - Berserker Rage

The Walking Brick
This guy can take a lot of hits...
5 - Dreadnaught
10 - Vampire
15 - Parry
20 - Smash
25 - Berserker Rage

Thanks guys for reading this guide! I know the formatting isn't the best and it wasn't in-depth, so please give me some feedback so I can improve in the future. I promise to release more guides for the other perks like this!

See ya later!