General overview

Phantom's kit is a smattering of elements borrowed from the other fast-redeploy operators at the time of his release, but his very high damage potential means he performs best when used as an assassin. What really sets him apart, though, is his clone, who functions as another fast-redeploy unit. The clone isn't a 1:1 replacement for an extra operator because its existence is tied to Phantom, and its redeploy timer works a bit differently. Once you get used to this, you'll find that the clone gives him unparalleled utility. He's more of a quality of life improvement than a core operator, but he makes so much of a difference that you'll wonder how you ever managed without him.

E2? Pretty much mandatory because of the significant reduction in clone redeployment time.

Talents

Talent 1 (Phantom in the Mirror) gives him the ability to summon his clone. Talent 2 (Phantom Mastery) shortens the redeployment cooldown of his clone by 10 seconds.

Something that is worth noting is that, unlike with normal operators (and even other summons), the redeployment cooldown on the clone starts ticking when it's deployed rather than when it's retreated. So, if you leave the clone out for 35 seconds or more, it can be redeployed instantly. This was assumed to be a bug when Phantom was released, but it hasn't gotten patched, so it's safe to assume this is just how it works now.

Skills

S1 (Phantom of the Night) gives Phantom Physical Dodge and a Shield that can absorb Physical damage proportional to his HP for 10 seconds. This skill is inferior to Gravel in pretty much every conceivable way.

S2 (Bloody Opus) gives him 9 stacks of an ATK buff. Every normal attack consumes one buff. Phantom does a lot of damage with this skill, even as the stacks start to wear off, and you can effectively double his output by using his clone on the same target. He can also stall enemies while doing a bit of chip damage, especially if you force someone to go through his clone first.

S3 (Night Raid) deals damage to all enemies in the surrounding tiles, pushes them away (force 0), and randomly inflicts either Slow, Stun, or Bind for a few seconds. The RNG makes it a little unreliable, but you'll get good crowd control if you're not concerned with what kind of crowd control you're getting. The duration of the effect is long, and you get some bonus damage with it. You can use his clone for another shot at the random effect as well.

Masteries

Phantom doesn't need masteries, but once you get to him, you'll probably want to stick to S2. M1 and M2 barely do anything, so you need to go all the way here. Most notably, he gets a 10th buff stack at M3.

S3 has very respectable gains at M3 (his damage and effect duration increase quite a bit), but most players will find it hard to justify.

Modules

Module X refunds 80% of Phantom's DP cost upon retreat instead of the usual 50%. This is huge for a fast-redeploy unit, especially for him since he's a bit more expensive as a 6 star. The upgrades reduce the redeployment time of his clone even further (-14 at mod2 and -16 at mod3), which is an excellent upgrade if you spam his clone a lot.

Module Y gives Phantom a 10% ATK buff when there are no allies in the adjacent 4 tiles. Mod2 gives both Phantom and his clone an additional 10% ATK buff if both are on the field. Mod3 gives his clone some stat buffs. This module is more useful if you're trying to wring as much damage out of him and his clone as possible.

Phantom's specialized module only applies to Integrated Strategies. It reduces the redeploy time of him and his clone by 1 second with each attack. Mod2 allows his clone to refresh his skill every time it's deployed (up to 8 times). After Mod3, his clone will no longer take up a deployment slot. If this module sounds busted on paper, it's even more busted in practice, which is why it only applies to IS!