This is a version we wrote of this scene way back in about 2007 or 2008. As it turned out, our story and characters evolved so that we didn't want to use it this way. But it was too good to waste, so here it is as the final intermission strip after Episode IV.
Episode V will begin with the next strip.
Luke: R2, lock the targeting computer onto the exhaust port.
Obi-Wan: Hey, wait a minute.
GM: You can't talk to him, Ben. Chewbacca flew away with Han.
Obi-Wan: So I'm Obi-Wan's ghost or something. This is important.
Obi-Wan: I've been looking through the rulebook. If you aim with the targeting computer, you only hit the port indirectly, so you don't get credit for it.
Obi-Wan: But if you do it without the computer, you get XP for the Peace Moon and everyone who's caught in the explosion.
Luke: Seriously? Let me see that.
GM: What the deceased Obi-Wan has neglected to mention is that without the targeting bonus, you'd have to roll a natural 20 to hit the vent.
Obi-Wan: He can use Force Guidance to add his Wisdom modifier to the attack roll.
GM: You should not be able to talk to him.
Obi-Wan: Use the Force, Luke.
Luke: It'll be so sweet if this works.
Tàrkin: Ah 'ave, 'ow you say, ze bad feeling about zis.