With the recent changes to the Engineer's trait lines, there has been a gutting of fringe builds that relied on the burning proc from Incendiary Powder to dish out the majority of their damage. For many many moons now, the "go-to" Engineer build has been one running both the Bomb Kit and Grenade kit, along with one utility of your choice (but given the abundance of warriors, this was usually something with a stunbreak). While many people choose to only run one of these kits, or neither due to the "spammy" nature of grenades and bombs, they are both extremely potent kits that should find themselves on almost any bar when you step into PvP. Here's why:
First and foremost, the beautiful thing about both bombs and grenades is that they double-dip on power and condition damage. So stacking hybrid stats and gaining Might stacks has heavy implications for boosting your damage as an Engineer. Moreover, both kits are exclusively AoE in nature ( meaning you have team presence and pressure on a node) and both kits stack an obnoxious amount of conditions on your enemies, providing you damage, and your teammates excellent cover conditions to prevent your important bleeds, burns, poison, and immobilizes from being cleansed.
Secondly, due to a distinct lack of stability and condition cleansing, Engineers do not make great bunkers. They are very solid at fighting on-point, and they can be made into fairly beefy tanks, but they do not make for good bunkers. No matter how much Vitality and Toughness you pack on; no matter how much vigor you have access to; no matter how prescient you are in foreseeing and doging your opponents knockbacks/stuns/fears/damage; the fact of the matter is that an immobilized Engineer is a dead Engineer. And no amount of dodges, blocks, and blinds will keep you on a point or off your ass when the other team's DPS comes a knockin'.
So what does this mean? That Engineers should be fighting small engagements on enemy points (due to excellent access to knockbacks and AoE pressure on node) or they should be fighting at larger engagements alongside teammates, but without a hard restriction that they must keep to the point. This causes a slight friction between whether you should be on or near the point laying bombs or off the point chucking 'nades, but gives you the ability to do both with great efficiency. Let's dive in and discuss the kits that are the foundation for this style of play!
Toolbelt: Big Ol' Bomb - Set a timed charge with a big blast the launches nearby foes.
The bomb kit is a versatile close-range weapon kit that brings excellent conditions and utility to the table. While the auto-attacks has an incredible power-scaling coefficient, the frequency that people will actually get hit by it is abysmally low, so it tends to be better to shift into the kit, lay down any combination of the 2-5 abilities, and swap out to another kit to keep the pressure going. Fire Bomb is a low-cooldown fire field that can cover most a small node in Conquest-style PvP, and puts out excellent damage as it stacks burning on the target. Concussion Bomb, when it hits, can deal thousands upon thousands of damage to your opponent as they continue to use skills not realizing they're chunking away several hundred HP every time they take an action. Smoke bomb is a slow-pulsing large AoE smoke field allowing for some excellent stealth plays or simply blind spamming to help ensure a stomp or prevent a nasty CC from hitting you. Glue Bomb is a large AoE that has a brief immobilize upon first activation, and cripples targets who remain in its animation while it persists. The Bomb Kit has no real rotation of abilities, other than popping into it every 10 or so seconds to drop the fire bomb and whatever else is off cooldown/fits the situation, or after laying down a Big Ol' Bomb to immobilize your foes into a nasty knockback.
Toolbelt: Grenade Barrage - Throw several grenades at once.
The single most important ability to bring as an Engineer is the Grenade Kit. Whether you are running a condition damage, power damage, hybrid, or butt-naked build, you should *always* bring the Grenade Kit for team PvP. On that note, though, you must also bring the trait Grenadier from the Explosives trait line. Coupled together, this kit goes from being kind of okay to being an absolute necessity. The difference between a good Engineer and a poor one is almost entirely found in their ability to utilize the grenade kit correctly. Every single one of the abilities is fantastic, and you should rarely be using your primary weapon set when you're packing this kit in your loadout.
First off, is important to note that this kit has no auto attack. You must manually activate and target the #1 ability every single time you wish to use it. This has serious implications when it comes to mouse longevity, development of carpal-tunnel, and for the lonely guys and gals out there how much romance you'll be shamefully experiencing later at night. (*cough*) In spite of this, the #1 ability is very important to constantly use as it does excellent AoE damage, stacks vulnerability to aid in future direct damage, and/or cover more important conditions, and can proc burns, bleeds, and all manner of nasty things depending on your traits. Beyond constant spamming of the Grenade ability, each of the other grenades in the kit should be used on cooldown. Shrapnel grenade does fantastic power damage and stacks several long-lasting bleeds while being on a very short cooldown. Blind grenade is great for spreading blinds to targets that are about to use heavy-hitting or hard-CC'ing abilities, and keeps pesky Storm Spirits from insta-gibbing you. Frost Grenade can stack massive amounts of chill on a target, completely ruining their day, and hits like a truck as well. And Poison Grenade does miniscule damage, applies a very brief poison to an impacted target, and leaves behind several *enormous* completely ridiculous poison fields. Every second an enemy remains in one of these fields, they get about 8 seconds of poison applied to them. So a poison grenade toss coupled with a brief immobilize could easily lead to 30+ seconds of poison stacked on a target. Grenade Barrage does excellent damage and can annihilate charged blocks from Elementalists or Guardians and allows condi-damage Engineers to have a potent spike of direct damage to finish off low-health targets.
So why bring both kits? Flexibility. While a build could be better optimized for either team-fighting or side-point pressure, the overall utility, AoE damage and condition application, and general lack of oompf in other trait setups leaves Bomb/’Nade Engineers "streets ahead" of almost any other Engineer loadout. While you may not be an unkillable monster in 1v1 battles, you will be packing plenty of tools to remove enemies from nodes via knockbacks or pressure, while still bringing excellent damage and options for your team. Bomb/Nade setups may not be the be all / end all of Engineer builds, but Engineers are definitely the be all / end all of Guild Wars 2 classes.