Groups with at least one electronics player get huge damage mitigation buffs if they use Smart Cover. The master mod for Smart Cover allows you to retain the buffs while out of the cover. So your opponents will deploy smart cover, quickly get into cover, quickly get out, and retain the buffs for 10 seconds (there is also a radius, but it's large).
Counter: As soon as you see Smart Cover deployed, destroy it. Sticky flashbangs are very effective for this. I haven't tried EMP grenades but I assume they work well too. Experiment with your friends and find effective ways to get rid of Smart Cover and negate those buffs.
Critical hits provide insane amount of damage compared to the base. I'm able to get 500k+ damage when I critically headshot an NPC with my Deadly+Brutal M1A. If you see players with high stamina also dishing out high DPS, it's likely a combination of pulse critical hits and accurate headshots.
Many players depend on pulse for critical chance. This makes sense because a good pulse will give you 80%+ critical chance allowing you to focus attributes and weapon mods on other things. As with Smart Cover, a good electronics player in your group can give you 100% critical chance! Every shot is a critical hit!
Counter: The pulse scrambler will prevent them from pulsing you and gaining the buffs. I used to think the pulse scrambler is only useful for hiding, but that's a secondary benefit. The real benefit is countering your opponent's pulse buffs in close quarters combat.
Burning, Shocking, etc
Skills like the shock turret and incendiary things (grenades, ammo) will prevent your opponents from using their skills. This is what makes the Sticky Flashbang so powerful. It's not so much about blinding the enemy as it is preventing them from getting the buffs they need.
You should favor skills that prevent the opponent from using their skills for any amount of time and that affect multiple players as much as possible. This allows you and your teammates to use your guns for maximum DPS.
Counter: Increase resistances (burn, shock, exotic). The downside is the lost gear attributes so this would be very useful in a group where one of your members is the bullet sponge tanky guy. I use a mask with a talent that removes all status effects with a medkit.
This is considered by many to be the defining factor in a PvP fight (all other things being equal). The more Defense Links you have, the more likely you are to win.
There isn't a direct counter to Defense Link. There is an indirect one though: tactics. Here are some rules you can follow (your mileage may vary):
- Never use Defense Link before a fight. Only use it when you're about to be defeated. Do not waste your Defense Link too early.
- If the opponent pops their Defense Link, stop shooting. Reload all of your weapons and run away to cover. Dodge their shooting while they try to rush you. As soon as their Defense Link is exhausted, counter-attack! Their rush will often put them in a vulnerable position.
- When using Defense Link, rush a single player on the opposing team. If you can't kill them, force them to waste their Defense Link in a panic. Sometimes they'll waste two by accident!
- The group member with the fastest cooldown (psssst: electronics build!) should use the Defense Link first. The group member with the slowest cooldown should use it last.
There are some interesting attack/defense buffs that I don't see mentioned often. For example, the "Critical Save" medical talent will give you a 40% (wow!) damage buff if you use a medkit at low health. You should practice using medkits at low health anyway so win-win. Or "On the Move" which buffs your damage mitigation if you a kill an enemy while moving (happens often in PvP).
There's even a talent that will set multiple enemies on fire if you set one of them on fire. Imagine a 4v4 PvP fight: other team rushes you, you equip incendiary bullets, hit one guy, and everyone is on fire. RIP.
Another I really like is an electronics build with a sticky bomb. Already you'll be dealing out a ton of damage. Now combine it with a talent called "Chain Reaction" that increases explosion damage by 40% if you hit multiple targets. It's perfect for nailing groups of 4 trying to extract at the same time.
Hope this helps someone!