This turian antimateriel[sic] rifle is modified to kill Reaperenemies. The Krysae's scope uses a rangefinder that adjusts to keep the target in proper proportion to the shooter, which comes in useful when the sniper is forced into close range. Its specialized ammunition is both armor-piercing and explosive. In a desperate move, the turians released its specifications over the extranet so that nearly anyone with a fabricator could manufacture this weapon to help the war effort.
This rifle has a noticeable travel time between firing and hitting targets, so compensation for the target moving must be made. However, unless the target dodges a significant distance, the proximity fuse will explode when it gets near anyway.
Despite the weapon description mentioning that it is armor-piercing, the rifle in fact has no base penetration. It does, however, deal 150% damage to armored targets.
The Krysae has a proximity fuse and deals area of effect damage in the form of an explosion - this can be utilised to not only shoot enemies behind cover by aiming above their heads, but also to damage large groups of enemies.
However, the proximity fuse means that if the bullet passes near any enemy, it detonates. This means that it is very tricky to shoot enemies that are behind other enemies, such as targets, or more dangerous opponents. Ravagers are particularly difficult as the projectiles detonate as they pass over the Swarmers that come from the Ravager's sacs.
Its proximity fuse is very effective against fast moving enemies like Phantoms and Nemeses.
Due to the proximity fuse on the bullets, it is impossible to headshot a Guardian in normal fashion by shooting through the slit - the bullet detonates in front of the shield, and the Guardian takes no damage. A tactic to overcome this is to rely on the area of effect damage by shooting at a surface near the Guardian, but not so close that it detonates prematurely.
The proximity fuse will even detonate when it passes near cloaked enemies - this makes the weapon very effective against Phantoms and Geth Hunters as you can shoot near them and it will damage them.
Due to its proximity fuse, screen shake due to teammate powers such as Shockwave does not affect its accuracy as shots will detonate if they get near an enemy.
The explosive rounds mean the Krysae is incapable of headshots.
This weapon works best when it can be spammed into a choke point, as this maximizes the usefulness of the weapon's explosive area of effect.
Although the explosion is visually large, the area of effect damage radius seems to be relatively small.
Additionally, this damage bonus works very effectively when combined with the area of effect damage - an Infiltrator can weaken groups of enemies by firing into the middle of them, allowing their teammates to mop them up.
Enemies are completely destroyed when killed because of the Krysae's high explosive rounds, making it useful against Reaper forces as it denies Cannibals bodies to consume.
Beware of enemies with plates, though, as the plates seem to protect the target from the Krysae. Aiming for their feet may keep the explosion from hitting the plates, allowing it to do full damage to the target.
Brutes can block the Krysae with their big claw. Aiming wide and/or high can bypass this.
Versus the Valiant, the Krysae has a far lower damage per second rating and its projectiles do not hit instantly, but it has a small explosive radius. The explosive nature of the shots allow the Krysae to be far more effective when employed against Phantoms, or clustered enemies. The Valiant however has a much quicker rate of fire, much quicker reload, hits instantly, and can kill enemies quickly, but does less damage than the Krysae. That being said, if you wish to be more of a person who kills annoying insta-kill enemies, then the Krysae is definitely a good choice.
Balance changes on July 24, 2012 drastically decreased the performance of the Krysae by reducing its damage, rate of fire, and spare ammo as well as increasing the recoil by 100%. This changed the Krysae from being a crowd controller to a support weapon, bursting enemies in cover and delaying enemy advances.
The Krysae's current low rate of fire can be ameliorated by using Marksman, available to the Turian Soldier and Quarian Marksman Soldier. This allows it to become a viable weapon for these characters, though probably not their best sniper rifle option.
The Krysae also works well with the N7 Paladin Sentinel's Snap Freeze ability, allowing the user to quickly dispatch of groups of frozen/chilled opponents.
The Krysae was originally designed to have a scope that auto-zoomed on targets for easier aiming. According to Mass Effect 3 lead combat designer Corey Gaspur, the mechanic was abandoned because it ended up making players motion sick: "If you were aiming at six guys, it was going in and out and in and out, and it made people nauseous."