taking back plays

[Toad]

Depends on when his lands were tapped, doesn't it? If he taps three lands and then announces the spell, he's got three floating when you back it up to announcement.

No, that's just rule cheesing to me. The player tapped his lands with the intent of playing his spell, so tapping mana is directly correlated with the casting of the spell, and is henced backed up too.

[Pern]

The player tapped his lands with the intent of playing his spell

You don't know that unless he taps them after announcing the spell.
The way most people do it is really bad form.

Announce the spell,
identify the mode and the targets,
use mana abilities and pay for the spell.
The correct procedure is in the rules.

[Jebus]

I'm not going to force someone to take mana burn on an illegally played spell.

I don't know many judges that will.

[Pern]

Tendrils guy comes up one spell short,
and has three mana of the wrong color floating.
He could have payed for the last one differently,
spent it all, and killed you.
Just to make it fun, he's at three life.
He floated mana, and then played his spells.
Gonna let him back it up?

OK, now it's the spell before the last one that he needed to play differently.
Gonna let him back it up?

The 2003 comp rules did relax this,
but I think encouraging players to do it properly
reduces the problem with corner cases.

[Jebus]

Tendrils guy comes up one spell short,
and has three mana of the wrong color floating.
He could have payed for the last one differently,
spent it all, and killed you.
Just to make it fun, he's at three life.
He floated mana, and then played his spells.
Gonna let him back it up?

OK, now it's the spell before the last one that he needed to play differently.
Gonna let him back it up?

The 2003 comp rules did relax this,
but I think encouraging players to do it properly
reduces the problem with corner cases.

I'm not talking about corner cases here.

[Toad]

Announce the spell,
identify the mode and the targets,
use mana abilities and pay for the spell.
The correct procedure is in the rules.

I actually *know* how to cast a spell... There are procedures, and there are real life ways of playing. You don't say "Pass priority" ten times per turn in a real game as you have to on MTGOnline, for example. There are shortcuts and acceptable plays. Some rules are written, right. But rules are just guidelines. In your first situation, It's pretty clear that the player tapped mana with the intention of casting his spell, so backing up includes untapping lands.

Your Tendrils situation is pretty different.

[Khahan]

It's pretty clear that the player tapped mana with the intention of casting his spell, so backing up includes untapping lands.

Your Tendrils situation is pretty different.

No, the game backs up to the point right before he cast the spell. Technically, in this situation, backing up does not untap the lands. Backing up takes you to a point with mana floating in the mana pool and the spell is back in your hand, unannounced.

Would I then allow the player to take back the land tapping?  That depends on the tournament and the player. At an FNM if its a newer player or little kid, sure, take it back and learn how to do it.
At a larger scale tourney or against a player that I know should know better, probably not.  I've been playing since Unlimited and if I do something like that, too bad for me. I should know better.

[Jebus]

I have no trouble reversing those mana abilities.  I probably only wouldn't at REL5.

I don't see this discussion going much further aside from just a back and forth, being that it is slightly subjective.  So, I think it's time to end it.