In the IPG, it says under definition:

A player illegally puts one or more cards into his or her hand and, at the moment before he or she began the instruction or action that put a card into his or her hand, no other Game Play Error or Player Communication Violation had been committed, and the error was not the result of resolving objects on the stack in an incorrect order.

Could someone give me some examples of situations where other Game Play Errors are committed, and how that affects the ruling?

Originally posted by Toby Hazes:

Could someone give me some examples of situations where other Game Play Errors are committed, and how that affects the ruling?

The easy example would be casting Divination for 2U when Thalia, Guardian of Thraben is on the battlefield. Technically, drawing those cards shouldn't happen; casting Divination was illegal, so the cards are being put into the hand illegally by extension. But, since it was illegal to cast Divination for 2U, this is treated as GPE-Game Rule Violation rather than GPE-Drawing Extra Cards. (Another example might be Chalice of the Void set to 1, and Ponder. Ponder normally wouldn't resolve in such a situation, thus the illegal draw wouldn't happen.)

One prominent feature of this is the opportunity to catch the underlying error before the card draw actually takes place; when Divination is cast, both you and your opponent (especially if he's the one who controls Thalia) could detect the error before you get to the point that Divination resolves. If this is the case (the error could have been cause when the spell was cast/ability was activated), then the infraction shouldn't really be GPE-Drawing Extra Cards.

There are situations where this philosophy doesn't work; such as drawing for a non-existent Howling Mine. There's no physical object involved here, so nothing to detect in terms of an error prior to the card draw actually happening. But, do you get the jist?

If, for example, a player activated and resolved the second ability of Sensei's Divining Top in response to Krosan Grip targeting it, could this also be a situation where a GPE was committed before the illegal card draw (In this case a GPE-GRV for activating an ability when prohibited) because the player controlling the Top and the player controlling the Krosan Grip both could detect the error before the ability resolved?

Yes. They illegally activated the Top, since a spell with split second was on the stack, so that would be an example of a GRV rather than Drawing Extra Cards.

A classic example - and one of the cards that led to this concept, originally - is Silvergill Adept. Playing that for 1U, and drawing a card, without revealing a Merfolk, is a GRV, not DEC.

Thanks for the answers =)

Does it matter how quick a card or ability is resolved? For example, if the opponent is tapped out, the player casts Divination for 2U and draws cards immediately, even through the opponent points out Thalia almost immediately?

So drawing a card with Elvish Visionary while Humility is on the board is a case of GRV?

Edited Toby Hazes (Feb. 11, 2013 05:58:43 AM)

Originally posted by Toby Hazes:

Does it matter how quick

Only in your investigation (if that's appropriate). It really isn't a factor re: whether to apply GRV or DEC. (And, as soon as I say that, someone will imagine a corner case to prove me wrong… :p )(Oh, and - I hope no one considers that an invitation to post corner cases!)

Originally posted by Toby Hazes:

So drawing a card with Elvish Visionary while Humility is on the board is a case of GRV?

Yep, and that's probably a good example of why. While a lot of judges will understand the relationship between Humility and EtB triggers, we have to expect that players will get that wrong - as an honest mistake. In fact, a not unlikely occurrence could be Amos plays Visionary, Nick (being the sporting type) says “sure, draw your card” … and a spectator does their duty, stopping the players and getting a judge. (Comp REL, obv.)(see below for correction…)

Edited Scott Marshall (Feb. 11, 2013 11:53:15 AM)

Correction! (I plead “Monday morning mental lapse”…)

In situations like that, where the first noticeable error is the card draw itself, it's DEC.

My first clue should have been your original post, Toby - where you quoted and even bolded the “no other Game Play Error” part. There is no other GPE (nor CPV), the error is the card draw itself.

It wasn't entirely clear for me yet so I asked for an unlock =)

I would like to know where the difference lies exactly between the Sensei's Divining Top and the Elvish Visionary example. In both cases, an ability goes on the stack that is not allowed to go on the stack, and the card drawn is a result of resolving this ability. The difference I see is that the Top is an activated ability and the Visionary is a triggered ability. So activating an ability when you're not allowed to is a GRV, but putting a trigger on the stack when you're not allowed to is not a GRV?

Edited Toby Hazes (March 1, 2013 10:20:59 AM)

The difference is not activated vs. triggered.
In the case of the Top, the first indication that there's something wrong is tapping the Top to draw a card; the opponent has an opportunity to prevent the error at that point. Activating the Top, with a Split-Second spell on the stack, is the “other” GRV that precedes the card draw.
In the case of the Visionary, the first indication that something is wrong is when the card is drawn - in effect, the error is drawing the card, and there is no “other” GRV at that time.