Author's background

120,000,000+ EXP playing [Trinity]
Top 500 Overwatch Support Player

Guide Notes

EV [Trinity]: minimum duration

Mods

Necessary mods: Transient Fortitude, Blind Rage, Fleeting Expertise, Overextended, Vampire Leech, Streamline.

• [Corrosive Projection] (CP) is generally the best mod in the game (when doing Eidolon Hunts, however, you may choose to replace CP with Enemy Radar, Dead Eye, or Shattering Impact, depending on your setup/loadout)
• Take [Natural Talent] and [Handspring] for a SIGNIFICANT quality of life improvement (take into account Trinity's ability cast times and how often you cast EV as well as how often you get knocked down in the game)
• [Handspring] can be replaced with [Coaction Drift], [Cunning Drift], or, ideally, [Primed Sure Footed] (Primed Sure Footed provides 100% knockdown RESISTANCE; however, it is a Daily Tribute reward (400th login... even I don't have it yet!)
• Personally, I prefer Quick Thinking over Vitality because in end-game you are one shot anyways, and [Quick Thinking] prevents you from dying no matter what. However, [Quick Thinking] or [Natural Talent] can be replaced by [Vitality] or, ideally, Umbral Vitality. It's up to you. Keep in mind that unlimited EV casts means unlimited Blessing casts anyways.
• [Adaptation], Rolling Guard, or Stretch can also replace Quick Thinking or Natural Talent, but you don't really need over 200% power strength
• [Primed Flow] is not required for EV because it would take longer to proc Vampire Leech (overshields) onto yourself with it equipped. Therefore, Streamline is the better option.

TL;DR

• [Corrosive Projection] (CP) is generally the best mod in the game (when doing Eidolon Hunts, however, you may choose to replace CP with Enemy Radar, Dead Eye, or Shattering Impact, depending on your setup/loadout)
• Handspring can be replaced by Coaction Drift, Cunning Drift, or ideally, Primed Sure Footed
• You may choose to replace Natural Talent and/or Quick Thinking with Umbral Vitality and/or Umbral Intensify or Stretch, but you don't really need over 200% power strength

Auras

• Take any Arcane you want, but I highly recommend taking Arcane Nullifier for Eidolon Hunts.
• When using a sniper, I recommend Arcane Momentum (this is what I run myself)

Gameplay

• EV [Trinity] is all about 2 (EV) and 4 (Blessing). Do not need to use 1 and 3. Personally, I use 3 when I need to know where the closest enemies are around me. That's really its only use.
• Spam 2 and 4. Do not use 4 more than once consecutively, or you may not have enough energy to cast Energy Vampire. A single 4 will get everyone on your team to full HP and shields due to the amount of Range and Power Strength that this build offers. Use 2 more often - remember, you are also restoring shields and giving your team OVERSHIELDS (Vampire Leech) by using your 2.

TL;DR

• Cast 2 and 4 alternately
• Cast 2 much more often than 4 as it can replenish shields and provide overshields due to the amazing Vampire Leech mod
• Never, ever, cast 1
• Only use 3 to quickly find out where the closest enemies are around you

If you have any questions, feel free to ask.
Enjoy! - HaventMetYou