Two men vomit when Mystique is fighting them
Although battle scenes are intense and we see people killed in different dark ways the over all violence is more fantasy than realistic, never-the-less the violence contains a significant number of deaths, in brutal ways. Blood is shown however usually just flesh wounds and little to no gore.
In the future we see evidence of the great battles that have brought civilization to its knees. Skyscrapers are crumbling, rubble is strewn everywhere and corpses tumble out of a container into a burial pit.
Bodies are impaled by robots with arm-like appendages, burned, blasted and otherwise killed. Slow-motion moments involve a person being slowly consumed by a blast of energy as they are lowered into it by a robot and another person exploding into thousands of pieces as he is overwhelmed by energy.
Pictures reveal mutants who have been tortured, operated on and sewn back together in Mengele-like experiments conducted by a scientist.
A character is executed with a bullet to the forehead (wound visible, no blood).
Wolverine has his chest riddled with bullets (leaving holes that then seal back up and the bullets drop to the ground). In turn, he impales his attackers with bone (pre-adamantium Wolverine) claws. He also hammers several human guards with a frying pan. (This is common in the X-men films for this character).
A man is pinned to the wall by his throat with a characters foot, he survives.
Through a variety of mutant-vs.-human fights, men are battered about with everything from hard-knuckled fists to floating metal balls, bones breaking and faces getting pounded.
There are also mutant-on-mutant melees. One mutant tosses another around in one scene, and pummels and tries to drown a different mutant in another.
Magneto levitates a needle to sew up a cut on the back of his own head.
A character is shot in the neck, leaving a bloody entrance and exit wound but survives.
A character is stabbed with metallic claws (open wound with blood visible). Another character states that she's lost too much blood.
A character is stabbed with a piece of metallic debris (wound not visible) from a resulting explosion. The character is slowly bleeding out as he's teleported to safety.
A character stabbed with multiple re-bars is thrown into a river and starts to drown.