If you kill his entire front rank on the charge, and you still have more wounds, they will be put on additional guys, and therefore the attacks are are not lost. However as long as you kill the first rank he can't attack you back, unless he has spears. And also, if you kill that many guys, you will win combat res so bad, it is not funny. You don't need the really high strength for dark elf heroes, as they have toughness 3. You can keep the temper virtue, as I am sure if you are rolling well it will help you alot. I would try to take something that gives you d3 or d6 wounds per hit, if you can. Or just take the lance with killing blow, to bad temper doesn't allow you to take magic weapons. Against the warhyrda, your lord will win because of the save. And if you charge it with a unit, it will die. However I suggest to charge his large blocks first. Make them run and persue after them. You can shoot the war hydra down so easily with a stone thrower(trebuchet). As it is s-8 in the centre, and does d6 wounds. That is better then sending your knights off to fight a random unit.