Bloodmagnet is a Blood-typed move.
It does what it says on the tin, really: Where regular magnets attract metallic objects, Bloodmagnet serves to alter the Blood-pokémon's state into one attracting blood. That being said, that's not its only effect it comes with and the characteristic symptoms of its use make that much apparent - it will draw its victims blood out through its pores. That being said, this only happens on areas of contact with the Blood pokémon, easily making this move one of the least dangerous of the Blood-type moveset.
A Bloodmagnet-charged pokémon will do a decent amount of additional damage each turn it makes physical contact, but it's not very severe. The base strength of each contact can be approximated to around 10.