A creature's ability can be used as many times as you can pay it, unless stated otherwise. If a creature has to tap to be able to use the ability, that will mean you need to untap it before you can use the ability again. Some abilities state they can only be used once per turn, others may state they can only be used "at a time when you can use a sorcery" meaning they can only be done in your main phases when no other effects are on the stack.
But in any other case, the creature's effect is instant speed.
There are over 1,000 legendary creatures in Magic: The Gathering.
Yes, in Magic: The Gathering, you can block multiple creatures with one of your creatures during the combat phase.
In a game of Magic: The Gathering, multiple creatures can block a single creature.
In Magic: The Gathering, you can copy a legendary creature, but if you have two or more of the same legendary creature on the battlefield, you must choose one to keep and put the rest into the graveyard. This is a rule to prevent players from having multiple copies of the same legendary creature, as they are considered unique.
Some popular 4-color legendary creatures in Magic: The Gathering include Atraxa, Praetors' Voice, Yidris, Maelstrom Wielder, and Breya, Etherium Shaper.
In Magic: The Gathering, multiple creatures can block a single creature. There is no limit to the number of creatures that can block a single attacking creature.
No, in Magic: The Gathering, you can only block one creature with one creature.
In Magic: The Gathering, the keyword "defender" means that a creature cannot attack, but it can block multiple attacking creatures at the same time.
Yes, in Magic: The Gathering, you can block with multiple creatures during the combat phase to defend against attacking creatures.
Yes, in Magic: The Gathering, you can block with multiple creatures during the combat phase. Each creature can block one attacking creature, and the defending player can choose how to assign blockers.
Yes, in Magic: The Gathering, you can block with multiple creatures during the combat phase. Each creature can block one attacking creature, and the defending player can choose how to assign blockers.
Yes, planeswalkers are considered legendary in Magic: The Gathering.