Only battle damage dealed to the player is treated as 0. If your Opponents monster is Mystic Tomato, Twin-Headed Behemoth, etc., you can get a monster, then both players still have a monster on the field after the Attack and the result is DRAW. You can use the effect of Sanga of the Thunder, etc. during the attack caused by this card's effect. If you control Jowgen the Spiritualist and activate Last Turn, you win because your opponent cannot special summon a monster.
your opponent can use Injection Fairy Lily's effect if he special summon her as his monster. If your opponent's monster is Witch of the Black Forest, and he gets a card in his hand using that monster's effect, and summons the monster in his Main Phase 2, then the Result is DRAW. Your opponent cannot get Gate Guardian, etc. If you activate Last Turn, and your opponent chains Offerings of the Doomed to destroy your only monster, than your opponent wins if he can special summon a monster. The player who activates Last Turn chosen his monster at resolution of Last Turn, not at actication, so your opponent will not know which monster to target with Offerings to the Doomed if you have multiple monsters. The effect of Rush Recklessly, etc., activated before Last Turn remaines in effect during the effect of Last Turn. This card "sends cards to the graveyard", it does not destroy them, for purposes of Toon World / Premature Burial (monsters remain) & Call of the Haunted (monsters are destroyed). With Last Will, Spear Cretin, and similar effects that get monsters, then the duel is a DRAW. If your opponent has no monsters in his Deck that he can spcial summon, you win. If Waboku was activated before Last Turn, then your monster is safe from the attack (posible a DRAW if your opponent special summons a stronger monster). If you control Dark Necrofear and activate Last Turn, even if your opponent destroys your Dark Necrofear (by special summoning Blue-Eyes White Dragon, etc.), your Dark Necrofear returns at the end of the turn as a Equip Magic Card, takes control of your opponent's monster, and you now have tha only monster on the field at the end of the turn and win the game.