My all purpose [Trinity] for Eidolon Tricaps.

You can consider this a general guide for Eidolon tips. This is specifically tailored for those that have limited resources/mods/arcanes, and how to get through your first Tricap with this [Trinity] build.

I know there are better specialized builds nowadays (a good starter build would be the Eidolons [Trinity] build by THeMooN85, for example) but this an evolved form of the EV build I used when Eidolons came out and it's what I use now to do some easy Eidolon public lobbies to help new players and clanmates. This is a generalized build for my play style, you may swap out mods with suggested ones further down in the guide based on what you have on hand or what works best for you. This a great build for me to use when I need Eidolon shards or I am looking to help some of my clanmates with a Tricap. (Or if I'm really in dire need of plat, easy arcanes.)

With this general build I keep the lures alive, I give shields to teammates and energy, avoid the pesky Magnetic procs, I'm helping my own DPS output with minor buffs and still have a decent survivability with overshields. This is specially nice in public lobbies since you don't know who is joining and is very flexible for swapping mods out for preset group loadouts (for those madlads that do 5x3 or 6x3 and use [Trinity] as part of their group loadout).

IT IS IMPORTANT TO NOTE THAT YOU DO NOT WANT FULL ARMOR STRIP ON YOUR EIDOLON HUNTS.

YOU WANT SOME ARMOR TO DOUBLE DIP ON FOR YOUR WEAPONS' RADIATION DAMAGE. IF YOU HAVE TO, REMOVE [Coaction Drift] AND ONLY RUN [Corrosive Projection] BY ITSELF WITH PRESET GROUP LOADOUTS.

A full explanation can be found through YT videos, wikis, ect., but the short of it is that Radiation damage on your weapon will do more damage if you keep some of the armor and don't strip it completely. (I find commonly that Trinity/Harrow runs Corrosive Projection/Coaction Drift combo and the buff frame runs a weapon/Holster Amp aura, and your DPS runs Dead Eye - keep this in mind when doing preset loadouts). For example, with a modifier of +75% against Alloy Armor, Radiation damage bypasses 75% of the target's armor and the base damage is also increased by +75%. Seeing how this is a build for all purpose Eidolon Tricaps (as in, you are playing all roles to some extent - DPS, buff, lure sitter) you want to make sure you make the job as easy as possible with little to no hindrances - keep that bit of armor and you will pump out more damage on those Teralyst Synovias AND when it comes time to pump Terry/Garry/Harry full of lead.

The actual build details:

To reiterate, this is a simple build I use for easy public Tricaps or for me to solo (I also swap out some mods for preset groups). I have a Rubico Prime with riven installed that I buff with a 3 second Roar for a quick and easy one-shot on all the Synovias, so take this build as a starting point and modify it for your use and your weapons. I recommend jumping in to do a Teralyst cap and see what you liked and didn't like and work from there.

This is a modified Energy Vampire (EV) build with [Vampire Leech]. Your main EV targets will be Vombalysts, and as a fair warning those have tiny hitboxes so make sure you have another way to [Regen] energy if you find you can't cast EV on them or they aren't nearby to spawn (they will be a constant mob spawning near your Eidolon as you bring them down, this should not be a problem). Maximum range and negative duration will take priority, but can be modified for your personal solo/ group preset use.

Range: max this stat as much as you can. [Overextended] and [Stretch] tend to be both slotted in for a basic EV build, but I usually only run [Overextended] in Tricaps. [Augur Reach] is another mod to slot in instead (this would replace Streamline) if you want to maximize range.

Duration: Make it as low as possible so that EV lasts 1.1 seconds - fast energy production, fast shield regeneration. I use a combination of [Fleeting Expertise] and [Transient Fortitude].

Strength: I slot in [Transient Fortitude] for the negative duration, but because of [Overextended]'s negative strength I slot in [Blind Rage]. The more your EV can pump out per pulse, the better for your team and their shields (and you!) so I suggest these 2 mods as the bare minimum. You can definitely slot in [Augur Secrets] for an extra 24% Power Strength instead of [Streamline] (if you happen to have it, that is).

Efficiency: With Fleeting Expertise slotted in your EV pulses will pump out energy and give Overshields with minimal energy usage on your end - I don't think it's necessary to slot in more efficiency mods, even if [Blind Rage] does almost [Negate] the benefits of [Fleeting Expertise] (without [Streamline], you sit at 105% efficiency). It's not necessary to slot in more efficiency as the ability pays for itself almost instantly. Alternatives for [Streamline]: [Augur Secrets], [Augur Reach], or [Flow] (or the Primed variant) for a larger energy pool if you desire it.

Survivability: I use [Primed Redirection] (used to be just [Redirection] until recently). If you have it and you're feeling fancy you can drop [Adaptation] for [Catalyzing Shields] (if you are not running Arcane Nullifier). This shouldn't be necessary but it's nice to know you have wiggle room in case you screw up a cast or your shields go down. I slot in [Adaptation] because I'm still living as a [Trinity] player from back when the lowest armor value was 15 and a toxin proc melted you instantly as [Trinity] (before she was given her Prime variant). I've seen some clanmates run Boreal's Hatred but run what you want for that second survivability mod - [Augur Accord] is another nice mod to slot it for extra shields and Overshield benefits.

Aura Slot: Corrosive Projection. Dead Eye. Rifle/Pistol/[Shotgun Amp] if you don't have a decent sniper. [Holster Amp] for all else.
Exilus: I use Prime Sure Footed because between Magnetic procs and knockbacks from all of the Eidolon's attacks/stomps/screams I'd be playing in Operator mode the entire Tricap. You can use regular [Sure Footed], [Handspring], [Kavat's Grace]. If playing with a group in a preset loadout, use [Coaction Drift].

Arcanes: I use Arcane Nullifier for that Magnetic proc and Arcane Momentum for my [Rubico Prime]. Some common ones I've seen usually have Nullifier with Arcane Rise, Arcane Precision, Arcane Awakening, or even Arcane Avenger. All of these arcanes buff shotguns/primary weapons or secondary weapons - as long as you are not using AoE weapons use what you can. If you don't have a fancy riven, I recommend [Hek] (or the Kuva variant), [Lanka], [Vectis] (or the Prime version), [Rubico] (or the Prime version) pistols with high damage per shot (I've seen some incredible [Knell Prime] builds for example, I'd check those out for some ideas). If you have decent rivens, mod for Radiation, slap on the appropriate arcane if you have it - otherwise, this is just QoL for you as a newer Tricap player.

Helminth: I use Roar, but I really doubt you need to do this if you're a newer player. You'll still be able to do a Tricap by yourself but with some extra work. I've done Warcry for an easy Vombalyst melee [Swipe] to charge lures when doing 5x3 or 6x3, but that is also unnecessary if you are running this build for solo runs. Link is fine to leave there as it is a visual cue for where Vombies are located and you need to charge lures.

Schools: I run Madurai. but if I'm running in a preset group loadout I swap to Unairu.

This is a basic build - follow it, tweak what you want, find your rhythm and use what you have. Not everyone can run the best mods or arcanes or rivens, and this build reflects that (to some extent). Keep in mind how flexible the build is meant to be, and try to understand that newer players won't be running Tricaps with groups unless they have maxed mods or special arcanes/mods/weapons/rivens. This was written for me to share with clanmates who struggle to do Tricaps, and I hope it helps others.