Is parry available in PvE

If you visit a bonfire or a lit torch in the environment, you use the action button (A on Xbox 360, X on PS3, Enter or Shift+Click by default on PC) to pull out your torch and light it. At a bonfire, you may need to press the "toggle" button (Y on Xbox 360, △ on PS3, N by default on PC) to show the button prompt to light your torch.

When you light your torch, you'll automatically hold it in your left hand, and it will stay lit until you put it away (by switching your left-hand item to something else). If you want to use it again after you've put it away, you'll need to find a bonfire or torch in the environment to light it again.

There is also a consumable item called Flame Butterfly that will allow you to light your torch anywhere by using the item from your inventory.

(And don't feel bad, it took me a couple hours to figure that one out, too.)

I'm a blue knight and yes I have to wear my ring for you to summon me and you must be in human form with your ring on to summon me. I've been summon from random places all across the map, even to areas I hadn't yet been too. The only place I wasn't summon to was the bell tower as that was a pvp area for the protectors of the bell covenant. If you were in that area, if you weren't human, if you weren't wearing the ring and one of us wasn't wearing our ring, that is why you couldn't summon one of us.

As for summoning and invasion The way it worked in dark souls 1 and dark souls 2 are different to make it more fair. It depends both on soul level and soul memory. Your soul level is what level you are while your soul memory is based off of how souls you spent on your armor weapon and levels. You can find it in your player status menu. It's to help fight against over powered people fighting under powered people.

Hope this helps and praise the sun.