My strategy was slightly different from the first comment, or exactly the same as another comment down the line. The 3 Valiants I fought (you can only fight 1 of each type every hour) were from Gnomeregan (Gnome), Stormwind (Human) and Darnassus (Night Elf). Since they have slightly different abilities, this strategy might not work with others but I will try nonetheless, for the hilariously named Lance a Lot achievement.
So here's how to do it, my style:
- Before I challenge a Valiant, I build up the full 3 Shield charges.
- Challenge the guy and immediately Melee him.
- Keep Melee-ing him, all the while making sure your 3 Shield charges are always up.
- When he starts to ride away, immediately throw a Shield-Breaker on him and immediately follow him. This will prevent him from using his own Shield-Breaker or Charge.
- Melee him again as soon as you get close.
- If you have less than 3 Shield charges, replenish them. Only replenish when you are Melee-ing him, since the Shield and Melee are on different cooldowns.
- Rinse, repeat.
- Gratz you've just kicked ass.