Blend In; They Know Me
Rather than attending a party alone, bring an extrovert. Someone who makes jokes. Accompany them wherever they go; they may not have been invited, but they will act as if everyone knows who they are. All night, listen to them laugh and joke. You might very well leave them there when they stop being interesting; they are having a good time. If you find yourself in discussion with others, you are not required to participate.
Simply saturate the other person with questions and let them speak for themselves. This should keep you occupied until you can flee. For a foolproof plan, find a chatterbox (there’s always one) and make them talk at you. Nobody is going to bother you. But be cautious: you may not be able to leave the discussion in time. If all else fails, pretend to have a bathroom emergency.