Archlord Zerato?

Question

http://yugioh.wikia.com/wiki/Archlord_Zerato

Here's his effect:

This card cannot be normal summoned or set. This card cannot be special summoned except by offering 1 face up Warrior of Zera on your side of the field as a tribute while The Sanctuary in the Sky is on the field. If The Sanctuary in the Sky is on your side of the field, discard 1 light monster from your hand to the graveyard to destroy all monsters on your opponent's side of the field. If The Sanctuary in the Sky is not on your side of the field, this effect is not applied.

My question is, how many times am I allowed to activate the special effect of Archlord Zerato? Is the ability to destory all monsters on my opponets side of the field by discarding a light monster from my hand limited to the one turn in which I summon Zerato, or am I allowed to use it once every turn?

Answer 1

it doesn't say "once per turn", so you can keep discarding a light monster for its effect. and it also doesn't say "on the turn this card is special summoned", so you can use its effect anytime (during your main phases of course)

Answer 2

You can use it as many times as you want, as long as you have Light monsters to discard.  Yes, you can use it multiple times per turn.

You can only use his effect during your Main Phase 1 or 2 though.