[Mesa]'s a mid level clear monster that can scale in to the steel path with some armour strip. If DE allows her to shoot something, that thing ain't living long.

Related builds:

• Regulators.

Abilities explained:

1: Ballistic Battery: A boost to a single shot that needs to be charged. Due to the low DMG cap it doesn't benefit mesa's 4 much but is an interesting build-around.
2: Shooting Gallery: A decent CC tool especially when mixed with [Muzzle Flash] a buff that always applies to yourself but also bounces between your teammates.
3: Shatter Shield: A great low level tanking skill as it provides 95% damage resistance (especially with pillage). Eventually it's not worth casting in endless.
4: Peacemaker: Press 4, hold left click, unleash hell itself.
P: passive: A tiny boost to firerate or reloadspeed based on what type of secondary you're using and an irrelevant amount of bonus exp if you don't bring a melee.

Notes:

• Do not even consider "building" around the passive. [Mesa] may be a [Gunslinger] but a good melee, especially a heavy attack one is a massive boon to any casters arsenal. The flat 50 hp you get from the passive is inconsequential.

Core:

Modded for balanced stats with max efficiency. Neutral duration is good enough for the 6 second stun of the Shooting Galley Augment.
Molt Augmented allows you to hit 200% strength without sacrificing any slots.
[Muzzle Flash] combined with the passive stuns from Shooting Galley and some range mods allow for a decent, passive crowd control effect.
[Enemy Radar] stacks well with [Primed Animal Instinct] allowing you to plan your engagements and never be surprised about what's around the corner, it comes in very useful if your companion ends up dying, also let's face it, auras as a slot suck, hard.
Arcane velocity saves you a valuable slot on your regulators (Allows you to remove anemic agility) and should absolutely be considered a core arcane.

Alternatives:

• [Augur Reach] is a flex slot, depending on the tileset and whether you're camping or not it can be swapped for a different augur mod (Message allows you to be more lenient with casts), secrets (for some a bit of extra umph), flow if you're having energy issues, or a wildcard like firewalker to allow for quicker traversal.
• [Mesa's Waltz], ONLY in circumstances where the use of your 4 is limited so that you can's spam it (Basically just ESO). Otherwise consider this mod in the non-alternatives category.
• [Primed Sure Footed]: [Vigilante Pursuit] offers more radar feeing up the aura slot for a different one. Power drift is another option allowing for easier stripping.

Non-Alternatives:

• [Pistol Amp], no matter how much sense this mod makes thematically it's a horrendous damage buff to any secondary but it's especially bad on [Mesa]. [Mesa]'s gets additive +dmg to her peacemakers from her strength. The 27% damage boost from the amp ends up being less than a 4-5% overall damage boost on a proper build. It's a sad increase and you get more damage out of simply using radar to find enemies faster.
• [Corrosive Projection], with armour stripping now being additive, corrosive projection is a dead aura on any frame that can fullstrip without it, and with a strip subsume mesa can do so.
• [Vigorous Swap], only triggers when you turn off 4, it's also additive with mesa's strength bonus making it both clunky and unimpactful.
• Swap speed mods are dead meaning you no longer have to bring them to make your 4 faster.

Economy:

Most of [Mesa]'s energy flows out for spamming her 4 (and subsumes) not channeling her 4. So max efficiency is borderline a must (But you can get away with as low as 130 if you want to trade the sustain for additional burst). Streamline and Fleeting shouldn't be maxed as skill cost cap at 1/4th of the original which is usually 175% efficiency (Max them if using blind rage). Duration mods help offset fleeting's curse while allowing your buffs to last longer.

Alternatives:

• (Primed) Flow: If you're having energy issues with energy not being reliably obtained you can substitute augur reach for flow.
• Arcane Energize: Further boosts to economy can be made by cutting one of the arcanes for energize. If you cut velocity, make sure to run anemic agility on your peacemaker.

Notes:

• Skill cost is capped at 25% of the original cost and the cost of channeling skills is effected by both duration and efficiency. Running these mods non-ranked saves you 5 starting energy per mod and running fleeting at rank 4 also gives you 10 duration with no draw-backs other than requiring you have a spare mod. Maxing them is fine, but if you can afford spares there's no reason not to go for R4's.

Survivability:

Mesas survivability comes from: killing everything faster than it kills you, shield gating, [Rolling Guard], jams from her 2, stuns from the augment and spoilermode (In that order). On lower levels shatter shield also does the job keeping you above health damage but that eventually falls off (in endless even not being worth casting at one point). [Primed Sure Footed] is mostly there so that you don't self stagger yourself with explosive weapons as during her 4 mesa is immune to knockdowns and staggers anyway.

Alternatives:

• [Brief Respite]: [Enemy Radar] can be swapped for brief respite. This is only really recommended if you cannot afford to slot any augur mods.

Notes:

• Warframe is a game where taking damage is mostly optional and revives are plentiful and are a resource to be used. This means that it's perfectly fine to die from time to time as long as you aren't failing missions.

Subsumes:

Pillage: Provides you with armour (and shield) strip that [Mesa] desperately needs for higher level content, another status cleanse outside of rolling guard as well as two shield gate reset per cast (assuming you're using an augur mod somewhere) the second reset being a large-gate reset. It's also cheaper to cast than terrify and the animation speed does not necessitate a boost.
Terrify: The best strip subsume in the game but due to it's longer animation it necessitates a boost in animation speed, as the mods are too tight for [Natural Talent] shards should be used instead.. With just 167% strength (which you have due to molt augmented) it fullstrips in a large area for just 19 energy.
Nourish: The best non-strip subsume. Provides a boost to economy as in increases all energy gain. Provides a damage buff for your weapons including peacemakers and CC's enemies when you get shot. It's a great subsume for steel path and below but does not scale as well as the strip subsumes in to endless.
Tharros Strike As cheap as pillage and comes with a 2 second stun but the healing is wasted and the area covered isn't as large as the above too.
Eclipse: A great damage boost for mid-level content but makes the build clunkier and is unreliable. At high levels you'll need a way to strip.
Fire Blast: It's just a worse pillage.
Roar: Costly and a relatively inconsequential buff if you're using banes (Decent option if you aren't but why wouldn't you be?).
[Xata]'s wisper Great for sentients but that's about it. As the stagger shield bug got patched you can no longer abuse it to force slash procs.

Archon Shards:

Mandatory shards: 1 Blue, energy max shard to give you a larger buffer with your pool (in case you're not going for [Flow]). For terrify, at least a single yellow casting speed shard is recommended as well.

Additional shards:

Red: Secondary Critical Chance, Ability Strength
Yellow: Casting speed (for Terrify), Effectiveness on Energy Orbs, Parkour Velocity
Blue: Energy Max

Note: Don't stack too many of a single one.

Gameplay:

Keep your 2 up as it stuns enemies. Cast 3 only if you're playing low to mid level content and have excess energy. Most of your time is spent jumping, casting 4, killing everything you can see, de-casting 4 then landing, if facing incredibly tanky enemies take some time to primed them with viral from your weapons as well as strip their armour with pillage or terrify. If you're getting shot at, use [Rolling Guard] then keep repeating the same process until you're bored of playing [Mesa].