They are the same as in TRIII.

SKIP LEVEL

Draw your guns, make a step back, a step forward, duck, stand up, turn around 3 times and then, jump forward

ALL WEAPONS

Draw your guns, make a step back, a step forward, duck, stand up, turn around 3 times and then, jump backward


If you don't draw your guns but do the sequence step back - forward - duck - turn around 3 times - jump forward or backward, Lara will explode. It will also happen if you draw anything else than the regular guns (the basic weapon, with unlimited ammo).