Magic: The Gathering; MTG. Regarding the effects of cards like Cursed Ronin/Grimclaw Bats/Midnight Covenant?

Question

So my question is.....

Where it says Tap a Swamp on Cursed Ronin (1/1) for +1/+1 until end of turn, could I tap 2 black mana so that way the creature becomes a 3/3 until end of turn?

Same applies for Midnight covenant which states Enchanted Creature has "Tap a Swamp: Creature gets +1/+1 until end of turn. Could I tap six swamps to increase the enchanted creature from a theoretical 1/1 to a 7/7 until end of turn?

I know generally the tapping of more mana consists of an X symbol to signify the ability to tap more than one mana, but it seems to me that I could do otherwise. I just want to clear things up.

Please be specific (if possible) and I will pick you as the best.

Answer 1

You can use the ability as many times as you can pay the activation cost. In the case of cursed ronin is to pay 1 black mana (from swamp, artifacts, etc). If you pay 11 mana, it will get +11/+11 EOT.

Midnight covenant is similar, but the cost is to tap a swamp. So the number of +1/+1 EOT will be limited by the swamps you tap

Answer 2

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Answer 3

Yes, you may tap multiple swamps to "pump" up Cursed Ronin.  The "X" signifies generic mana, not necessarily more than one mana.  Unless a card limits the number of times you may pay the activation ability cost, you may continue to pay it as long as you have the appropriate mana.