What is the best way to kill the Siren on Hard in Bioshock Infinite?
I had less trouble than I was expecting with these fights, even on 1999 Mode. I covered it in my 1999 guide, but I'll summarize here.
Lady Comstock takes critical hit damage from being hit almost anywhere, so critical hit boosting gear is very nice.
The Charge vigor, upgraded with the invulnerability option, makes this fight much easier. If you have Brittle Skinned as a gear option, the fight is downright trivial. Throw in a fully upgraded shotgun and the whole thing is over before she can summon her second set of goons.
- Hit her with whatever ranged weapons you have - I tended to bring a crank gun.
- When your shields are low, Charge her, which causes you to melee. This will activate invulnerability, plus recharge your shields. This also pops the Brittle Skinned bonus if you've got it.
- Unload your shotgun, and then fire off whatever else you can until your shields are down.
Once your invulnerability wears off and your shields are low, just Charge again. You could also retreat once the shotgun is empty, and reload your weapons and prepare to start from the beginning if that suits your playstyle better.
On 1999 mode, with around 5 infusion points into salts, I was able to take her down before I'd even halfway drained my salts or shotgun ammo.
The Charge upgrade can be somewhat expensive if you haven't saved your cash or prioritized it, but I didn't get it until just before this fight, and I just scrounged around the city, looking for enough change to afford it. There's a lot of ground you can cover in this area looking for resources.
You can use Vigors or set Vigor traps if you're having issues with her minions - Shock Jockey is pretty good for this. If you upgrade Charge with the explosive damage upgrade, you'll probably do pretty decent damage to them when you Charge anyhow. Bronco is my go-to crowd control option if things are getting hairy in close. When they're stunned, I believe they take additional damage, so if you've got a bunch of them on you, it might be useful to stun them to avoid wasting ammo.
You must fight her three times before she goes down, and I've listed the locations in my guide. It helps to go in fully loaded, upgraded, and healed, so knowing where she will attack can make a big difference.
If you kill any of her ghost soldiers normally, she can easily resurrect them. Kill them in such a way that they leave no corpse (Shock Jockey or Devil's Kiss). If you do this, her supply of soldiers will slowly dry up until only she is left. Upgrading the Shock Jockey to affect multiple enemies and using it in conjunction with Undertow will also speed things up significantly.
Weapon-wise, the Siren is very mobile so you don't want to rely on weapons that are accuracy-dependent (Sniper Rifle). The machine guns and shotguns are good options. And the volley gun's area-of-effect also make it a viable choice for dealing damage to both Lady Comstock and her minions at once, killing two birds with one stone.
Easiest way I found is, before the fight, lay 10 fully upgraded Devil's Kiss traps at Siren's spawn location. It will take her out immediately even on 1999 mode.
- First fight - Before you open the crypt: on the stone road outside the crypt a few steps from the round intersection.
- Second fight - When you enter the Vault's main hall area for the first time (right after you left the elevator): on the floor next to the side of desks in the middle of the hall close to the vault door.
- Third fight - Before you open the last tear: on the floor next to Lady Comstock's statue on the side where the gate is.
The only drawback is the high demand on salts. Luckily the map has many salt bottles lying around. And thanks to the many skylines and hooks, it should be easy to conserve them using the "Winter Shield" trick.
Here is it in action: