Magic the gathering question: if an ability doesn't cause a card to tap, can i use it more than once?

Question

for example, the card knollspine invocation reads as follows:

x, discard a card with converted mana cost x: knollspine invocation deals x damage to target creature or player.

since it's ability doesn't cause the card to tap can i play it more than once per turn as long as i have mana to tap and cards to discard?

Answer 1

as long as it does not have a tap symbol you are able to reuse it over and over again.  So abuse that ability as much as possible.

Answer 2

Yes, you may use the ability as many times as you want, provided that you can pay its cost. For example, you can activate the ability in Knollspine Invocation as many times as you want, as long as you have the mana to pay the X mana cost and you have cards in your hand to discard.

You can't play the ability without paying the cost.

Hope that helped.

Answer 3

As long as the mana is available for use and you still have the necessary requirements for the ability, you are allowed to use said ability as many times as possible.