The Grave of Saints is an area in Dark Souls 2 located in the large open pit in Majula. You can access this place with the help of Ladders or the cat ring.
The Royal Rat Vanguard is an optional fight found beneath the hole in Majula.
The Royal Rat Vanguard is a boss in Dark Souls II and is found past the second bonfire. This boss has a very similar appearance and size to the rest of the rats fought in the room. However, it has more prominent hair on its back. Some rats are all weak to Fire.
This boss is not that hard to defeat. The battle will start against many weak before the leader shows up. Use a large sweeping weapon to take care of the rats. Run to the fog wall once the bosses heath appears before he jump in. If you are quicker you will be able to launch the attack before he even moves.
SInce he has about 2500 health, therefore he will die very quickly. Keep an eye on hin otherwise he can get lost in the group. He has a distinguishing brown stripe of fur down the middle of his back.
For range character this battle may be a bit hard since there is no enough room to move around. If you are an archer characters you need to circles around the room, while mages should come in packing AoE spells.
Remember that the rats are weak so an AoE spells should do the trick. Also you can use Pyromancy to sort out the rats.
Once The Vanguard is defeated, the remaining rats exit from the arena.