Ok here is a question. At my local tourney there have been some debates on whether Jowgan the Spiritualist effect works with Last Turn. Most people say that when Jowgan is on the field and the owner activates Last Turn then the Field clears except Jowgan. And the opponent is not allowed to summon. So the Jowgan owner wins. The other people say that because of Jowgan's effect the owner in not allowed to activate Last Turn because Last Turn says that the opponent must Special Summon a Monster. Ok that is my dilema. Any help is greatly appreciated.

I'll just redirect you to another Thread where this has already been discussed in detail:

CLICK HERE

There, you'll find responses from Judges, which I suggest you print out to show to those who argue, because Last Turn does work with Jowgen.

Thank you very much. I will check it out and see what I can find out.

jowgan + last turn is very legal.

see, they are referring to the fact that effects cannot be activated if they will not do anything at resolution. such as playing raigeki when the opponent has no monster that raigeki can destroy, so this cannot be done.

but last turn isn't the same. at resolution all that last turn does, is select jowgan, and send everything to the graveyard. thats it, after that last turn is done resolving and the rest of the chain, if any, continues.(so, as long as last turn's player has a monster to choose, last turn can be activated)

then after the current chain finishes, you then do any other effects, such as witch/sangan, or other effects triggered during the chain. after all pending effects are finished, the opponent is then to summon a monster, and battle with the selected monster. jowgan prevents this, but that doesn't matter, last turn resolved, and doesn't care if what it put forward is possible or not.

the battle takes place in whatever phase last turn was activated in. then after the battle, the opponent's turn continues as normal, then when you get to the end phase you determine the winner, by who controls monster(s).

depending on when last turn is played, if sangan/witch got the opponent a monster, if they were in their standby phase, and retrieved sinister serpant, and they didn't summon yet, they can still summon, cunduct their normal battle phase, and win or cause a draw.