Energy Vampire has always been, and continues to be absolutely broken in a good way. She lacks the wide area nuke and pure room clearing power of other frames, and can be a bit on the squishy side when optimized for EV, but if you want to absolutely melt a single target, Trinity is your girl. She's one of the few frames that has an ability that does percentile true damage.

I don't play Trinity much because I have a natural aversion to buff jugglers (same problem with Gauss), but, she has some cool stuff in her kit that does make her quite fun to play.

First up, Vampire Leech combined with Nourish gives her excellent shield gating ability, for the whole squad, as overfilled energy will spill into shields. EV builds also have a purpose again with this strat. Very powerful. Energy Leech in general is very fun for new players who are still getting their energy economy toolkit filled out. The whole squad will benefit from at least 6000 shields and very high shield generation, and Trinity herself goes up to at least 24k. That's a lot of shields.

Instead of running Nourish/Vampiric Leech, Pool of Life lets you build Trinity as a chonky health tank before you ever need to think about Helminth. Only problem is it's slightly clunky, especially if you're pumping her duration to make her less spammy: it requires manual deactivation, while also trying to ensure the enemy has taken lethal damage while acting as a Well.

Link has the very nice property that it bestows status immunity, including knockdown immunity. If your crowd clear is too good though, say goodbye to your link and get ready for the self-stagger. This is less of an issue on Steel Path, but still a major bugbear with the ability due to how the status immunity behaves when Link swaps to a new target.

Blessing is the classic, of course. While it was nerfed some time ago to be basically useless for objective healing, being able to project damage reduction to the whole party and quadruple their EHP is quite nice. Plus the healing. If you bring a supply of Ancient Healers it's also possible to have a reliable "battery" for Champion's Blessing. If you're running Nourish this actually gives Trinity quite a good damage potential.

The passive is nice too, especially if you're running Vazarin and potentially even Amalgalm Shotgun Barrage.

Overall she's really good, and actually carried me a long way when I was still new, back in like 2016 or something. I mentioned in my other thread that her pace of play needs some tweaking. There's too much juggling and her casts are glacial. If you don't mind that though there's an absolute beast of a frame in there.

She also has a cool lobster tail dress on her Prime, so that rules. Trinity best lobster girl.

Edit:

I'll try and get a video up eventually with the specific Tankity builds I run. Can't recommend Vampire Chef Trinity enough.

Trinity's niche would be as a support frame, most effective in endurance missions like Survival and Defense. To a lesser degree, Trinity is also useful for Eidolon hunting and isn't a bad choice if you're playing public and trying to learn how to do these bounties.

While her general kit may be a little dated with the shift to Shield Gating, her abilities are still very useful for defending objectives and for providing your team with damage reduction. I think her main weakness is just how short her ability duration is for her 1st, 3rd and 4th abilities.

Well of Life:

• This is probably Trinity's weakest ability, essentially turning an enemy into a healing mote similar to Garuda's Blood Altar/Wisp's Health Mote, while also granting Status Immunity to allies within the Well's radius.
• My main uses for Well of Life are for to build Combo/Maintain for either melee weapons or snipers. Headshot gimmicks like Death Knell can also be proced on a Well of Life enemy. In a more recent update, Well of Life also gained the ability to protect allies from Status Ailments, my main use case for this is preventing Rad procs in defense-based sortie missions.

Energy Vampire:

• This ability deals True Damage, bypassing shields and armor, pairing well with Viral and actually benefits from having low duration.
• With the Vampiric Leech augment, this ability is easily able to replenish shields.
• Trinity built around Vampiric Leech has become my preferred Index build because of its good survivability, energy management and single target damage. The downside to focusing on Energy Vampire's single target damage is that Trinity's other abilities are heavily impacted by modding for negative duration.

Link:

• Transfers damage and Status to any enemies linked to Trinity.
• Provides 75% damage reduction.
• While not useful for fighting most Corups, the Abating Link augment is very useful for quickly stripping armor on linked enemies.
• Because this ability gives Trinity Status Immunity as long as it links to an enemy, I find it very helpful in Sorties with Radiation/Magnetic modifiers.

Blessing:

• Both heals and restores shields.
• Also provides 75% damage reduction to all allies within affinity range and is capped at 50% damage reduction for objectives.
• I find the Champion's Blessing too annoying to maintain because of the short duration and often hard to actually find something that needs to be healed to get the buff in the first place because of shield gating/Overguard. You can get around Shield Gating by healing a specter without shields like a Nidus Specter or Ancient Healer/Combat Discipline if you really wanted to use this augment, but Overguard will prevent you from taking health damage making healing a specter the only reliable way to get the buff (as far as I can tell, a specter can't be buffed with Overguard).

Trinity gets to boast a fun little niche as a Boss Unit killer, with the % health damage in her kit. High Strength (300+), very low Duration, with a Viral primer. Prime your target with 10 Viral stacks, cast Energy Vampire on them, and watch them explode. The main places where you'd utilise this are against Demolishers in Disruption, and Thrax in Void Cascade, though you can also pair it with the Marked for Death Helminth subsume to turn it into an area nuke. Due to the % health damage it doesn't fall off as levels go up. It's very silly and very fun. Not super practical, as with such low Duration only your 2 and 4 remain viable in her base kit, and you're limited on what you can subsume, but grouping abilities are generally fine with low Duration so remain a good subsume (and the crowd control from pulling and displacing enemies can be vital to helping you survive in Void Cascade. In Disruption you generally run Vazarin so you're fine, Void Cascade encourages Madurai)

Trinity is more or less required on a squad farming Grendel.

never grinded her out on pluto, but I did nab her prime at one point exclusively for eidolon hunts. I'm not really sure what other uses she has that other frames can't do better. Energy Regen can be done so many ways (I'm a fan of Nezha w/ Synth Fiber and Equillibrium), and healing kind of isn't really all too critical - content is either too easy to warrant it, or too punishing for it to make a difference.