Is there a rule against combining Flash with Vigilance to attack infinite times?

Question

This might be a bit of a silly question, I'm not sure. I'm really new to magic, I've only been playing for a week. If I were to use a spell of some sort to give vigilance to a creature with flash or flash to a creature with vigilance, would I then be able to attack infinite times without tapping, killing my opponent instantly?

Since flash allows a creature to attack at any time, and vigilance doesn't require a creature to tap to attack. Or is there a rule stating that you can only attack once per creature per turn, unless you have double-strike? I took a brief look at the comprehensive rules, 302 (creatures) in particular, and did not see any such rule, which leads me to believe that this is legal, unless the aforementioned rule is under a different section. Again, this might just be a silly question.

Answer 1

Flash does not "allow a creature to attack at any time." From the comprehensive rules:

702.8a Flash is a static ability that functions in any zone from which you could play the card it’s on. “Flash” means “You may play this card any time you could cast an instant.”

Flash is an ability that determines when you can play a card, but once the creature is on the battlefield, Flash doesn't have any effect.

Answer 2

No, you cannot attack infinite times with the same creature in a single turn (barring cards that grant extra combat steps).

From the Basic Rule book (p8):

Attacking and Blocking
During your turn, you decide which of your creatures, if any, will attack. You can’t attack with a creature if it’s tapped or if it entered the battlefield this turn. You have one combat phase in the middle of your turn, and all the creatures you decide to attack with attack at the same time. [emphasis added]

Neither flash nor vigilance override these rules.

From the Basic Rule book again (p14-15)

flash—You may cast a spell with flash any time you could cast an instant, even in response to other spells.
vigilance—A creature with vigilance doesn’t tap to attack. (Vigilance doesn’t allow a tapped creature or a creature that entered the battlefield this turn to attack, though.)

Also as a note, double strike doesn't cause a creature to attack twice just deal damage twice (this can matter, because some cards care about when or how many creatures attack)

Answer 3

Flash only modifies when you can cast the spell. This is true regardless of the card type. (You can find enchantments with Flash such as Dictate of Erebos).

Attacking is determined by the steps within the game:

1. Upkeep step - Pay any costs/ Untap permanents
2. Draw step - Draw a Card
3. Pre Combat Main Phase - Cast Spells
4. Attack Phase - Declare Attackers (opponent declares blockers)
5. Post Combat Main Phase - Cast Spells
6. End Step - Clean up

Creatures can only attack in the attack phase. It is possible to have additional attack phases with certain cards granting this: Aggravated Assault.

There are also cards that can grant you additional turns which is essentially giving you what you desire: Medomai the Ageless

To get unlimited attack phases, there are a combination of cards that can achieve this such as Neheb, The Eternal + Aggravated Assault + 5 damage.

Flash and Vigilance will not achieve infinite combat steps.

If you attack with a creature, you are declaring that you are in the Attack Phase and all phases before that have ended. Once you attack and damage is dealt the attack phase ends and you cant attack again that turn, unless you have incorporated any of the above cards/ combos and fulfilled their noted conditions.