Baba Yaga DLC - Boss Fight (Part 2)

Loot the packs the witch's minions leave behind for ammo and other supplies. Then jump across the water to the far right (southwest) side of the room. Here you'll find the second vat (marked B on the map).

Notice that the lever that opens this vat is a bit farther away. So stand on the side of the spool nearer the lever. Then turn around to face the witch.

If the witch attempts to blast Lara with fireballs, jump out of the way.

Then return to the spool, shoot at the witch to make her duck down inside her cauldron...

...and then shoot the cauldron with a rope arrow to attach it to the spool.

Switch to the pistol or rifle if you like and shoot the witch again to make her duck as the spool draws the cauldron in.

While this is happening, run to the lever...

...shoot the witch again if necessary to prevent her from cutting the rope.

Then, when the cauldron is close enough to the vat, pull the lever...

...to open the vat and blast the witch across the room again.