Build and weapons demo

This is a Merulina build, if you don't want to ride Merulina you're better off with a different build, or a different frame. Yareli is The Waverider, not The Beachwalker.

Playstyle/Abilities

• Cast 2 to board Merulina
• Find some enemies and cast 1
• Kill enemies using your secondary weapon to proc Merulina Guardian
• Keep moving to keep Yareli's passive 200% crit damage up
• Recast 1 regularly to maintain buff and crowd control (can be cast during battery weapon recharge)
• If you find a nice large group of high damage enemies, cancel and recast your 2 and let them all hit you for a bit - Merulina's health scales with damage received (you are immune) in the first few seconds after casting, so this will give you a tankier Merulina for the rest of the mission. At stupidly high enemy levels (above 6000 or so) you want a slightly less tanky Merulina so that incoming damage will kill Merulina before killing Yareli - recasting is less annoying than reviving. This is not important for tha vast majority of players.

Her 3rd ability, Aquablades, is okay on low levels, but doesn't really do much at Steel Path, so I Helminth over it with Chyrinka Pillar for when I have to defend an objective (like an excavator). You can cast two of these at a time to slow/radiate two lanes of enemies.

The 4 is useful for grouping enemies, but the 'pull in' part of the ability only applies for a couple of seconds after casting, rather than throughout like Vauban's Bastille ability.

Weapons

Secondary - The best weapon for [Yareli] is the [Sporelacer] kitgun. If you've not played [Yareli] with [Merulina Guardian] and a [Sporelacer], you've not really played [Yareli].

The build I use is:
[Sporelacer] + Haymaker + Macro Thymoid
[Hornet Strike]
Galvanised Diffusion
[Primed Target Cracker]
[Primed Pistol Gambit]
Pistol Pestilance
[Primed Convulsion] (I use a riven with Electricity instead of this, we want corrosive damage)
Primed Heated Charge
Primed Fulmination
Lethal Momentum
Pax Charge
Cascadia Overcharge
Options -> Accessibility -> Fire Manual Trigger Weapons Continuously

Any crit based secondary weapon will work, and Yareli will make them all feel great. I also like the Dual Coda Torxica, Occucor, Scyotid, and Knell Prime.

Primary - Nothing that really helps [Yareli] here. Some people like the [Afentis] for the area buff to reload speed, fire rate and recoil when thrown, but it’s only temporary and I found it annoying to keep dismounting and resummoning Merulina. I use the Dera Vandal because I have a good riven for it and it can use the Soaktron skin, which fits the theme a little.

Melee - any Furax variant with Amalgam Furax Body Count (for secondary weapon fire rate).

Effect Of Stats

Strength - mostly for the damage increase to enemies captured by Sea Snares, but also increases Merulina's max health and healing done by proccing Merulina Guardian. Strength does not affect the fire rate/reload speed buffs from Merulina Guardian.

Duration - only useful for length of Merulina Guardian buffs, and to recast Chyrinka Pillar less often.

Range - affects how far Sea Snares travel towards enemies, pull distance for Riptide and Chyrinka PIllar radius..

Mods

[Combat Discipline] is used to reliably proc [Merulina Guardian] (which requires Merulina to have taken damage) and Arcane Avenger. If you keep the [Combat Discipline] mod at rank 2 (or below) then you take no damage from it, because 90% of the damage [Yareli] takes is absorbed by Merulina's life pool, meaning only 10% is taken from your life. So you lose 10% of 4 health per enemy killed, which means you lose 0.4 health, which the game rounds down to 0.

Augur mods - Energy spent on abilities is converted to shield and allows you to gain overshield, which is necessary for Cascadia Overcharge to work.

Primed Vigor - I like it, but if you don't, or if you don't have it, or if you want to save forma, substitute it for Augur Accord or standard Vigor. You want enough shield to get your companion above 1200 shields with Link Redirection.

Streamline/Flow? - [Energy Nexus] works better for [Yareli] because the main skills you’ll use only cost 25 energy, and if you for whatever reason lose your Merulina you will want to get back on it as soon as possible, energy [Regen] can save your skin in these situations. Don't take any energy efficiency because you still want to be spending some energy to proc the Augur mods.

Arcanes

Arcane Avenger for crit chance and Arcane Velocity for fire rate.

Arcon Shards

Azure archon shards are the only source of armour (3 × 225 armour) that also applies to Merulina. The two emerald shards are so you can fully armour strip enemies with your weapon (2 × 3 additional corrosive stacks, though normal shards will also do).

Companion

I use a Sahasa Kubrow with the following setup:

Link Redirection - to get over 1200 shield.
Reinforced Bond - for 60% increased fire rate now that it has over 1200 shield.
Tenacious Bond - for +1.2x final crit multiplier (which is multiplicative with other crit damage mods).
Dig (the reason I switched to the Kubrow) - for bursts of energy and ammo if using a different secondary weapon.
Link Redirection - to trigger Reinforced Bond.
Elusive Posture (on claws) - to stop it getting itself killed as often.
Bite (on claws) - to get crit chance on pet high enough for [Tenacious Bond] to work.

Then whatever other mods you want, I use:
Primed Animal Instinct
Link Fiber
Restorative Bond
Enhanced Vitality
Resourceful Retriever
Fetch

Operator/Drifter

You can use the Zid-an Uskos Tektolyst Artifact to get a bit more fire damage for your guns, but otherwise none of them really affect the build.

Focus school doesn't matter at all. I use Madurai so my amp can easily kill void angels etc.

Low investment / New players

If you don't want to throw loads of forma at the stupid k-drive frame, or you're new to the game and can't access the mods used in the main build, here is a 0 forma setup and MR2 weapon that works:

[Combat Discipline] (Rank 2)
[Merulina Guardian]
[Intensify]
[Vitality]
[Steel Fiber]
[Energy Nexus] (or [Streamline])
[Augur Accord]
[Augur Reach]
[Augur Message]

For the weapon, I recommend the [Sonicor] (blueprint available on the market) with;
[Hornet Strike] (Rank 8)
[Pistol Elementalist]
[Barrel Diffusion]
[Fulmination]
[Heated Charge]
[Pathogen Rounds]

This setup also uses 0 forma and I've tried to choose mods that are available fairly early on in the game. Better builds for the [Sonicor] definitely exist if you want to invest more.