Excal's the game's poster boy, his 4 is still powerful enough to blend pretty much anything DE considers "content" provided you build him right.

Related builds:

• EXALTED BLADE
• COMBO STATSTICK

Abilities explained:

1: Slash Dash: Become invulnerable to health damage, dash forwards and hit everything in front of you once procking slash. If your 4 is up add the wave attacks to it.
2: Radial Blind: A standard AOE CC stun, can be casted with a slide attack during your 4 for less energy but with less range.
3: Radial Javelin: A horrible skill with an amazing augment, hits up to 12 enemies around you for almost no damage. The augment increases melee damage multiplicatively for each enemy hit.
4: [Exalted Blade]: An outdated ability outclassed by most modern melees but still shreds. An exalted [Skana] that shoots waves of energy to kill your opponents.
P: [Excalibur]'s passive is a minor boost to attackspeed and damage of swords.

Core:

[Furious Javelin]: a massive, separate multiplier that works on your 4. Don't underestimate this augment just because it's tied to a horrible base skill.
[Chromatic Blade]: A massive boost to damage, as well as a decent, passive CC option that also makes you less reliant on priming enemies.
[Umbral Intensify] and Molt augmented provide you with enough strength to fully strip with the subsume (167% ) as well as for your 4 to do a decent amount of damage.
(Archon/Prime) [Continuity] makes buffs last longer while decreasing the cost of your channeling. (Archon is better on the corpus variant)
Stretch and augur reach together allow your CC/strip abilities to hit more enemies and [Furious Javelin] to gain stacks easier.
[Melee Guidance]: Abusing an exploit on how gladiator mods works in a combination with a statstick redeemer allows you to have consistent high tier crits on your exalted blade. Click the link for more info.

Alternatives:
Alternative Auras: [Enemy Radar] is always handy for information gathering. [Combat Discipline] can enable arcane avenger shenanigans. [Brief Respite] makes shield gating easier.
[Energy Conversion]: An old excal staple from when stripping armour wasn't as readily available. Because the current subsume is somewhat spammable rather than being a long-form buff it's not recommended on this build. If you're going for one of the buff subsumes drop some range and run it.
On a grouping build [Stretch] can be substituted with [Archon Stretch].

Economy:

Unlike Umbra and Prime the base energy of base [Excalibur] is not enough to run this build. This is why we're running 2, blue archon shards as a core part of the economy of the build.
[Streamline], combined with [Primed Continuity] helps get the price of your 4 down and the eff helps with the strip spam.
Energize serves as a backbone of your economy, and if worst comes to pass you can always drop a pad.

Alternatives:
Without the archon shards you need at least [Flow] on the build without dropping other economy related boosts. If you're on one of the buff subsumes you can also simply swap streamline with flow/primed flow as they aren't as energy hungry as terrify.

Survivability:

Rolling guard and Spoiler Mode (Lockdown+Repair/Elevate) are all you really need. Terrify's CC is also very handy but keep in mind it doesn't work on CC-immune eximus units. Abuse shield gating for stray shots with an augur mods (Some can be on your secondary). If a hallway's not fully dead during the 3 sec RG provides instantly spolermode to lockdown the remaining enemies. [Sure Footed] allows you to use exploding primaries as well as to prevent you from getting stunlocked.

Alternatives:
[Handspring] if you don't have [Primed Sure Footed].
[Cunning Drift] can allow you to drop [Augur Reach] and still have decent range but make sure you have at least one augur mod on your or shield gating becomes a lot harder.

Subsumes:

What skills to swap: Either Slash Dash or Radial Blind. Slash Dash's can proc a decent number of procs in a hallway and works as an emergency button. Your 2 can be casted for less of a price by doing a slide attack while your 4 even if you replace it. Neither skill is vital for the function of this build so you can pick between them based on the content you're planning to play as well as the subsume you're choosing.

The subsumes can be split in to three groups. Stripping, Buffs and Grouping. If the subsume has a built in crowd control component, swap 2, otherwise swap 1.

Strip:
Terrify: With the armour strip changes in the game terrify became the premier strip skill. It's relatively expensive but provides a full strip at just 167% strength while also fearing all enemies.
Pillage: Pillage does arguably more than terrify but does not easily fullstrip. It's cheaper to cast, refreshes your shields twice usually maxing them out on the second instance. It's a very good option. at 200% strength which you have with maxed augmented you fullstrip with 2 casts.
Fire blast: The weakest of the three. Mediocre crowd control and decent but not amazing strip usually reserved for builds that play slightly below 100% strength.
Buffs:
Eclipse: Massive damage increase especially considering it's multiplicative with all other damage buffs including [Furious Javelin] although reliability varies from mission to mission.
[Xata]'s whisper: adds a second damage instance, an additional CO proc, makes enemies easier to hit, makes enemies block each others gunfire, reset sentient invulnerability. The down sides are that the waves will keep orbiting the same enemy until they expire, meaning you lose some points in the hallway clearing category while gaining some level DPS (not against armour though).
Warcry: Find a way to squeeze in its augment and you got yourself one of the best mindless subsumes for low level clear. The attackspeed buff with the augment is refreshed as you kill with waves so you only have to cast it once helping your economy. The downsides are that the damage buff is minor and the armourboost is worthless.
Roar: Energy hungry and the damage boost isn't great if you're running a banes but I thought I'd mention it due to the double dip anyway.
Grouping (not really recommended but worth the mention):
Larva: Group enemies but ragdolls them meaning worse electric procs.
Ensnare: Requires a target and sorta slow but it's decent crowd control and doesn't ragdoll.

Archon Shards:

Red: Melee Critical Damage, Ability Strength, Ability Duration
Yellow: Casting Speed, Effectiveness on Energy Orbs, Parkour Velocity
Blue: Energy Max

Gameplay:

Start off by getting x12 combo on your 'deemer statstick and casting your 3 buff and 4, after that, it's a balancing act, keep track of your javelin (and subsumed buffs if any) buff(s), your energy, and your melee combo, as well as stripping tanky enemies. Although the build can comfortably have everything active all the time some focus and effort on the players part is required to keep the economy going and the health bar full. The damage is fairly good so you shouldn't have issues with downing enemies. If in a scrape, use slide attacks with your 4 or terrify to blind enemies in an AOE, rolling guard to either help you escape or hold your ground and spoiler mode in order to to reposition or stun.

Notes:

• Because 1 makes you immune to health damage you'll almost never have shields once it ends so if you can't use [Rolling Guard] once you're leaving it use operator mode or cast it again as soon as you can or you'll be dead on the spot (at least on higher levels).
• 1 can also be used as a decent movement ability as well as an "oh sh*t" button, buying you time to reassess your current situation.

Q&A:

Q0: Why not just use umbra/Prime?
A0: Umbra's passive removes most of his buffs every time you use spoiler mode and with a glass cannon build like this you're expected to be doing that often. On top of this even if you build for facetanking the AI umbra cannot use arcane [Guardian], [Adaptation] nor shield gating meaning he dies incredibly fast. As for the prime, well, that's simple, I don't own a functioning time machine... yet. But if you own the prime by all means use him, he's the best excalibur. Just swap Primed flow for streamline.

Q0: What if I want to build for a non-chromatic build?
A0: Subsume warcry, slot [Eternal War] instead of [Chromatic Blade]. This is done due to the unreliability of the slash build's procs increasing the chance of procs by simply rolling for them more often.

Q1: Why is there no HP/armour/facetankmod#177013.
A1: Because DE doesn't know how to balance the game and shield gating+rolling+Spoiler is so strong anything with 1 shield doesn't need additional survivability.

Q2: I keep getting killed and....
A2: Git gud.