THE ONI STORMGUARD
Proceed to trigger a scene. After this, the final boss fight takes place; you're up against a powerful Oni Stormguard warrior, who's also backed up by Stormguard archers. This fight consists of three separate phases.
The first phase is a one-on-one battle between Lara and the Oni Stormguard. He will approach Lara and swing his mighty club in her direction. Needless to say it's imperative you avoid his attacks. Fortunately, the Oni is slow and you can easily outrun him. Nonetheless, you want him to attack you since his back is vulnerable and exposed after each swing. Jump-run away after each attack, quickly turning around to briefly fire at his back. If you have any grenades, save them for the next two phases. After softening him up, move in for a finisher (with Y or Triangle).
In the second phase, two Stormguard archers join the fight, and they'll be replaced by new archers when you (or the Oni) kills them. The archers are so dangerous, however, that you'll want to grab your shotgun and try to remove them from the field most of the time. The same strategy still applies for the Oni. If you have any grenades left, there's no better time to use them than right now. Be sure to get a red reticle before blowing them into his upper torso, though, to ensure they're doing damage. Needless to say you'll want to be at some distance when doing this. Like last time, move in for the finisher whenever he's own.
The third phase is similar to the second, but now you can also damage the Oni by shooting his face. He'll cover it with his arm after an instant, but it'll be exposed again soon enough. The other strategy still applies in this face; stay on the run, dispatch the archers with your shotgun, use any grenades you might have left on the Oni while keeping your distance, and you'll soon enough get the go-ahead for the finisher. A short QTE (Y, tap Y, tap X, or Triangle, tap Triangle, Square) will finish the fight.
After this it's only a matter of going to the center of the area and performing the following QTE correctly: RT, Y, tap X, alternate LT/RT while moving the camera towards your target.
Congratulations, you've beaten Tomb Raider!
At this day camp you can find [SHOTGUN SHELLS], [HANDGUN AMMO] and [RIFLE AMMO]. Proceed and climb the tower; this ascent is, no matter how spectacular, fairly straightforward. As you reach the top, various Solarii guards will come at you. Defeat them (look around for [SHOTGUN SHELLS] and proceed. A second wave of enemies has to be defeated before you con continue. Short triple bursts with your handgun work well here. Tempting as it may be to kill the two riot shield guards with grenades, you might want to save those for the final boss fight.