Are Sentinels outclassed by Explorers or is it just me?

Nah... Each of the six profiles bring their own playstyle really.

Soldier is your typical gunslinger with a few tools to make it even better, plus grenades. They actually require some tactical management of special ammo and power cells.

Biotic is your control type. Locking things down and then making them go boom... A lot.

Engineer is your versatile type that has a tool to take down enemies of every type, whether shielded or armored. Plus pets.

Infiltrator is your stealth/sniper like always.

Vanguard is your up close and personal class.

Sentinel is your high risk/high reward "spam the crap out of Nova and Lance with no cool down/eats shields upgrade" build with the tech armor providing extra protection.

Explorer is your all around build for those who like grabbing things from each section and has the best evade in the game.

Since the matter of power combos came up, how do I make them stronger? I'm running Sentinel 6 profile, took all the "+combo damage" passive evos, use Throw with "+30% combo damage". On the first glance, it about doubles the basic damage combos do, and they still can't kill a basic mook on Normal. It comes to absurd situations like setting mooks on fire with Incinerate will kill them 100%, but if I detonate the effect, they'll live through it.
Not sure what else I can do to that end, other than stuffing my gear full of "+combo damage" augs. I'd really like to avoid that.

As an explorer pretty much all your bonuses are really useful. Can't say the same for combo detonation damage, construct damage, or even weapon accuracy/stability.

Adept works because biotic powers actually do damage and you got echoes. Biotic lance to the head does a good chunk of damage. Pull does 600 base damage to shields plus the containment bonuses.

Tech powers simply do shit damage. Overload fully charge does a fraction of shield damage compared to Pull, which makes no sense because the entire reason for overload to exist is as a shield stripper.

So in the tech tree, your best skills are energy drain, invasion, and tactical cloak by far. Energy drain is tech's equivalent of biotic charge, and invasion and tactical cloak are massive damage output boosts.

It's just a shame powers are so gimped compared to weapons in this game, because it kills most of the tech tre: Who the hell uses the cryo or fire throwers on insanity? Almost nobody.

Incinerate is only decent against fiends and krogan enemies. A piranha with invasion and tactical cloak will still do far more damage (hell, even a sniper will).

Tech powers alone aren't all that powerful, but there are more to them than just damage.

Overload, for example, isn't the best shield stripping power in the Tech tree. It's a combo detonator that has the option for CC with chain "lightning."

Energy drain, by itself, isn't that great of a shield stripper...but it's a primer. Tech combos are VERY good for stripping shields. Powers alone won't kill that quickly, but add in a bit of gunplay, and your powers supplement your bullets and vice versa.

Energy drain also has some crowd control ability if you tech burst it. It leaves a decently sized electrical field on the ground that has a DOT component as well as staggering non-shielded/armored enemies. It almost feels similar to the DOT on Singularity, plus it seems to do more damage vs shields compared to health.

Add in the Sentinel's Combo Damage bonus, and you're looking at shields stripped, fire explosions, staggered enemies, some minor but decent crowd control, burning enemies that take more damage from your weapons, plus weapon damage bonus after casting tech powers, and you've got a really good "generalist" build that doesn't rely on one single trick, but has tools for pretty much all situations.

Does it match Turbocharge with a bio-converter'd Piranha? Not for sheer damage output, no, but it's a very fun playstyle that has different explosion effects going off near constantly, enemies flying around the map everywhere, with a lot of survivability to boot. Energy Drain/Incinerate/Throw on a Sentinel profile is my favorite playstyle so far. Charge Vanguard is too in-your-face for my preference, and I don't like relying on one "trick" to beat everything. Turbocharge and + Weapon Damage builds are the same. Undeniably powerful, but based around one trick that just...kinda gets old after a bit.

Piranha and Dhaan are overpowered even without seeking plasma.

It's dumb that one is betetr off going explorer, grabbing tactical cloak and eitehr turbocharge/invasion, and rounding that off for biotic charge with biotic warrior perk and pretty much melting everything.

The only time a sniper is ever useful is when dealing with a Kett Ascendant or Remnant Destroyer.

It's just dumb that snipers do such pitiful DPS even with headshots compared to shotguns right now.

Infiltrator is the least gimped of the tech profiles BECAUSE it is a weapon based profile for the most part with the tech recharge bonus merely being for tactical cloak or invasion.

But Engineer and Sentinel have real stinkers for profile bonuses because the base constructs and damaging powers just suck in a major way.

I do. Cryo beam is lots of fun, an ineffective crowd controller with the added bonus of debuffing armor. And Overload with a 3x multiplier to shields does comparative shield damage to Pull (and it too can be further boosted by passive skills), not to mention it primes and detonates (which despite combos being weak in general, against shields Tech explosions are not bad). Sure you can just use powers that buff weapon damage, but that gets boring and on most enemies its just over kill. 

To be fair though i use explorer myself, but im sure there are effective sentinel builds out there. Also with that being said Tech, Fire, and Cryo combo damage more then probably do need a buff. It would be pretty hard to depend on those combos to reliably take out enemies. 

I disagree.  I just finished the Meridian mission on Insanity at around level 55 - around 80% to 90% of my damage output was from powers+combos.

- Sentinel profile rank 5 (or might have been 6, leveled up in the middle of the mission)
- Remnant gauntlet w/ +25% combo dmg
- N7 chest w/ shield oscillator, kinetic coils
- fusion mod of deployment (+50% faster power recharge)
- N7 arms w/ +4% combo dmg, hover aug
- N7 legs w/ +4% combo dmg, jump melee aug
- Heleus helmet w/ +6% combo dmg

- PAW w/ +20% power dmg on full clip
- Piranha

- All tech and biotic passives maxed
- Fitness combat passive maxed
- Evo priority was combo damage or adding priming/detonating, recharge speed, power damage

- Max Cryo beam for Shatter rank 6 evo (appears to buff Remnant gauntlet freezing)

- Active powers are energy drain, incinerate, and either charge or throw.

One power rotation of energy drain -> incinerate (tech combo, re-primes) -> charge/throw (fire combo, throw re-primes health) was either killing a red health bar mook, or leaving it with a sliver of health (easy to mop up).  Powers were recharging for another rotation after only a second or two of the last - about enough time for one or two punches or a couple of pot-shots with a gun.

Or charge -> melee (freeze unshielded mook) -> energy drain (cryo combo, re-primes) -> incinerate (tech combo, re-primes) -> charge again (fire combo) will kill any unshield mook.  Often dead on the incinerate.

One energy drain + throw/charge tech combo was stripping the shields from observers and anointed.

That build is also very tanky, and when using charge you just fly around the battlefield non-stop, never bothering with cover - except against destroyers and architects.  For stuff with melee instakills I'll switch to throw.

I was gonna switch to angaran arms and legs armor to add some +tech dmg, but ran out of Heleus research data.  Was using more biotics earlier.  Speaking of, you can do an all biotics build and use all biotics and biotic combos for most of your damage output - lance / annihilation / charge is one example.

Which ever way you want to do the bulk of your damage - you have to really build for it and stack every possible bonus on armor and weapons, and in passives.

Oh, and I have also been dragging Peebee along more recently - for her widespread 25% defense debuff w/ Invasion.