Drakuseth, Maw of Flame's ability, and other abilities that start with "when ~ attacks" trigger when the creature is declared as an attacker, not when they deal combat damage. So double strike does not affect the ability, and it would only trigger once regardless of rather or not it has double strike.
Take note that Drakuseth's ability does not 'activate'; it triggers.
Triggered abilities are somewhat out of your control: they come to life 'because something happened'.
Drakuseth, for example, will deal a bunch of damage 'because it attacked'.
When it attacks, it triggers, whether you like it or not.
Activated abilities, on the other hand, are fully under your control: they come to life 'because you say so'. Metropolis Sprite, for example, will gain +1/-1 if, and only if, you say 'I want my sprite to gain +1/-1 and I will pay the blue mana'.
Take note that Drakuseth's ability does not 'activate'; it triggers.
Triggered abilities are somewhat out of your control: they come to life 'because something happened'.
Drakuseth, for example, will deal a bunch of damage 'because it attacked'.
When it attacks, it triggers, whether you like it or not.
Activated abilities, on the other hand, are fully under your control: they come to life 'because you say so'. Metropolis Sprite, for example, will gain +1/-1 if, and only if, you say 'I want my sprite to gain +1/-1 and I will pay the blue mana'.
See rules 602 & 603 for details.
To phrase it a little more simple...
Triggered abilities generally have the words “If, When, At” in them, and are ‘triggered’ by something happening. I.e. - When __ dies... At the beginning of combat... If you would draw a card...
Activated abilities have a cost, and you choose when to do them. They are worded as “2B: Draw a card”
Triggered abilities generally have the words “If, When, At” in them, and are ‘triggered’ by something happening. I.e. - When __ dies... At the beginning of combat... If you would draw a card...
No, triggered abilities strictly use "when", "whenever", or "at". For example, "When ~ attacks", "Whenever you gain life", "At the beginning of your upkeep", etc. Delayed triggered abilities will use the same words, but they'll often be in the middle of a sentence instead of the beginning.
"If" is not used to indicate a triggered ability, although some triggered abilities have intervening 'if' clauses in them which can prevent the trigger from being put on the stack at all or prevent the trigger from doing anything as it resolves. Bloodhall Priest, for example, will not even put the trigger on the stack if you have cards in hand at the time when it enters the battlefield or is declared as an attacker. Abilities in the form "If...instead" indicate a replacement effect.
Triggered abilities are somewhat out of your control: they come to life 'because something happened'.
Drakuseth, for example, will deal a bunch of damage 'because it attacked'.
When it attacks, it triggers, whether you like it or not.
Activated abilities, on the other hand, are fully under your control: they come to life 'because you say so'.
Metropolis Sprite, for example, will gain +1/-1 if, and only if, you say 'I want my sprite to gain +1/-1 and I will pay the blue mana'.
See rules 602 & 603 for details.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules
To phrase it a little more simple...
Triggered abilities generally have the words “If, When, At” in them, and are ‘triggered’ by something happening. I.e. - When __ dies... At the beginning of combat... If you would draw a card...
Activated abilities have a cost, and you choose when to do them. They are worded as “2B: Draw a card”
"If" is not used to indicate a triggered ability, although some triggered abilities have intervening 'if' clauses in them which can prevent the trigger from being put on the stack at all or prevent the trigger from doing anything as it resolves. Bloodhall Priest, for example, will not even put the trigger on the stack if you have cards in hand at the time when it enters the battlefield or is declared as an attacker. Abilities in the form "If...instead" indicate a replacement effect.
Two Score, Minus Two or: A Stargate Tail
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