By enacting Rayne's "feed" attack, so long as an enemy is vulnerable (meaning it isn't holding a large weapon with which to smack her down), Rayne will pounce on the poor schmo and dive straight for the jugular. This is how Rayne gains health throughout each level, and in the process, she can also reload her blood guns by pressing the fire button while drinking up. Once you're done with your blood donor, you can either toss that enemy aside or kill him or her in spectacular fashion by using one of Rayne's execution moves. By performing one of a few different button combos, Rayne will do anything ranging from simple stabbings to out-and-out slicing and dicing of an enemy, sending limbs, torsos, and heads flying every which way. These moves are gruesome and hysterical, though unfortunately, there aren't a ton of them--only 12 in all--so they do get a little repetitive after a while. http://www.fut15mall.com/
Wesley Snipes comparisons aside, Rayne has more than enough talent to put a stop to her own vampire apocalypse--even if this one doesn't feature Stephen Dorff at the forefront of it.
Fortunately, this is not the only method of execution the game provides you, because Rayne has several contextual moves she can use to put the pain on the bad guys as well. For example, Rayne can slide down certain pipes and rails, and while she is sliding, you can make her extend her blades outward, thus sticking any enemies that might be standing along her slide path. Another example involves Rayne's chain attack. Several puzzles in the game require you to clog or jam an object--such as a wood chipper or a garbage truck--that is blocking your path in order to pass. How do you do this? By sticking a baddie with your chain and flinging him into the aforementioned object, resulting in a bloody mess. There are also all sorts of sharp objects you can fling enemies into outside of kill puzzles. Rayne is a nimble little minx, and she can hop, skip, and jump all over levels with Prince of Persia-like precision. Every single level in the game contains at least a few lengthy jump puzzles, which feature bars she can hang from, pipes she can climb up, and so on. From these bars, Rayne can angle herself in such a way that she can shoot enemies from her perched position, thus making her tough to shoot. Aiming this way is a little tricky at first, but it works well enough once you get used to it.