Introduction

Firstly I'd like to note that this is a work in progress, I do not personally play Engineer but I feel I have come somewhere close to creating an unstoppable Engineer build for PvP.

About Unstoppable Engineers: After spam queueing BGs for events, gold and prestige I noticed some enemy Engineers, not many but a few, were impossible to kill with my Slinger - I just couldn't touch them before one of their allies nuked me down. This was particularly a problem in Halls of the Bloodsworn BG as the Engineers in question would cap secondary control points and spam over the control point so we couldn't cap and could take on 3-4 of my allies and only go down to 80% health before the enemy team showed up and pulverised the group. After a bunch of research (and trial and error with an Engineer guildie) I figured out the best way to achieve this unkillable pain in the ass build for Engineers. You wont do much damage, but you're a nuisance to the enemy team and an almost unstoppable force.

Abilities

Support:
(T8) - Great Tier 8 skill; deals a little damage as DoT, Blunders 5 foes every 1s for 6s and the Blunder applies a 33% chance of enemy attacks to be deflected for 3s, Applies a debuff that decreases CC resilience by 16% for 3s and If hit by 3 ticks enemy becomes snared reducing movement by 42% for 3s.
(Base) - Usable after a deflect, deals damage to 5 foes.
(T8) - deals damage that bounces to additional targets, instant cast when between 30 - 70 Volatility, grants a defence for 5s that decreases damage taken by 10%.

Utility:
(Base) - Deals a bit of damage and applies a stun to 5 foes preventing any action for 2.5 seconds and destroys 1 interrupt armour.
(Base) - Removes all CC effects and grants absorb.
(Base) - Gives a defence and Empower to you and 4 allies and generates 5 volatility every 1s for 10s; Defence increases deflect critical chance by 7%, Empower increases critical hit chance by 7%.
(T8) - This the most important skill in your loadout. Deploys a Personal Defence Unit lasting 30 seconds at the targeted area, grants a defence for 5s, on expiration grants absorb for a whole bunch of time. Tier 4 increases charge count to 2 and tier 8 restores 24.4% health every 1s for the duration of the buff. This combined with the AMP "Try and Hurt Me!" is what makes you unstoppable, if you change anything with this build yourself, don't change them!
(Base) - Deals some damage and blinds 5 foes, increases chance of deflection by 20% for 3.75s and destroys 1 Interrupt Armour.

AMP Build

--not done--

Runes

Weapon
Elusion 6/6 + Suppression

Head
Elusion 6/6 + Impervious

Shoulders
Provoker 6/6

Chest
Defiance 6/6 + Shrug it off

Hands
Defiance 6/6

Legs
Lockdown 8/8

Feet
Elusion 6/6