If I turn a token using {{Turn // Burn}} in response to an opponent trying to populate it, does he/she get another weird? If so, does it change back?
No, if you kill the token they are populating, they can't populate and their spell or ability causing the population fizzles.
701.27. Populate
701.27a To populate means to choose a creature token you control and put a token onto the battlefield that's a copy of that creature token.
701.27b If you control no creature tokens when instructed to populate, you won't put a token onto the battlefield.
Quote from: Agrus Kos, Enforcer of Truth on September 09, 2013, 08:56:49 PM
No, if you kill the token they are populating, they can't populate and their spell or ability causing the population fizzles.
701.27. Populate
701.27a To populate means to choose a creature token you control and put a token onto the battlefield that's a copy of that creature token.
701.27b If you control no creature tokens when instructed to populate, you won't put a token onto the battlefield.
Didn't burn it, just turned it
Oh, I wondered why people have weirds in a populate deck!
This is what it says "The new creature token copies the characteristics of the original token as stated by the effect that put the original token onto the battlefield." So I would assume even though you turned it he still gets a copy of the original token.
Edit: The following scenario is wrong 🙀
Your opponent tries to populate his token. In response you cast the instant, Turn. Their token turns into a 0/1 weird. Then the populate effect resolves and they get another 0/1 weird token. At the end of turn, their original token turns back into whatever it was. The second 0/1 weird remains.
No, "To populate means to choose a creature token you control and put a token onto the battlefield that's a copy of that creature token." You choose the target as you cast the spell or activate the ability, responding by turning it doesn't do anything. If you were to kill it though (with {Burn}) they don't get the token.
Its the same reason when I {Giant Growth} a Centaur and populate it, I don't get a 6/6 Centaure token.
Found more rules for you to reference:
706.2. When copying an object, the copy acquires the copiable values of the original object's characteristics and, for an object on the stack, choices made when casting or activating it (mode, targets, the value of X, whether it was kicked, how it will affect multiple targets, and so on). The "copiable values" are the values derived from the text printed on the object (that text being name, mana cost, color indicator, card type, subtype, supertype, expansion symbol, rules text, power, toughness, and/or loyalty), as modified by other copy effects, by "as . . . enters the battlefield" and "as . . . is turned face up" abilities that set characteristics, and by abilities that caused the object to be face down. Other effects (including type-changing and text-changing effects), status, and counters are not copied.
110.5b The spell or ability that creates a token may define the values of any number of characteristics for the token. This becomes the token's "text." The characteristic values defined this way are functionally equivalent to the characteristic values that are printed on a card; for example, they define the token's copiable values. A token doesn't have any characteristics not defined by the spell or ability that created it.
They will get their original token. Here's some fun rulings, with bold to stress the important parts:
706.2. When copying an object, the copy acquires the copiable values of the original object's characteristics and, for an object on the stack, choices made when casting or activating it (mode, targets, the value of X, whether it was kicked, how it will affect multiple targets, and so on). The "copiable values" are the values derived from the text printed on the object(that text being name, mana cost, color indicator, card type, subtype, supertype, expansion symbol, rules text, power, toughness, and/or loyalty), as modified by other copy effects, by "as . . . enters the battlefield" and "as . . . is turned face up" abilities that set characteristics, and by abilities that caused the object to be face down. Other effects (including type-changing and text-changing effects), status, and counters are not copied.
110.5b The spell or ability that creates a token may define the values of any number of characteristics for the token. This becomes the token's "text." The characteristic values defined this way are functionally equivalent to the characteristic values that are printed on a card; for example, they define the token's copiable values. A token doesn't have any characteristics not defined by the spell or ability that created it.
Basically, the copiable characteristics of a token are the characteristics defined by the card that created it.
Quote from: Agrus Kos, Enforcer of Truth on September 09, 2013, 09:36:13 PM
Hahaha, I Keyeto'd Keyeto with my Modification.
The Force is strong with this one....
This is a layering issue. For the same reason that {giant growth}ing the token would not give you a +3 P/T version when you populate the turn effect does not change your population. This is because effects exist independant of both their source and target. Effects do not change cards, tokens, or rules, they only change how we treat and interact with them. This is the only concept in magic more complicated than the stack. Yes the stack is simple once you get, but remember before you understood it how ridiculous it sounded.