It's a fantasy role-playing game.

DM: You are Vex Vex'ahlia, a half-elf ranger . You are the member of the famous group of adventurers. Previously, The bard summons Bigby's Hand and places it between the druid and the pit fiend, using it as an Interposing Hand. Pike is still inside the mansion, having seen Percy stick his head and arm out to fire, then duck back in.
DM: Yes, you are. For the time being. Pike is inside the mansion right now. She watched Percy step into the door frame, fire a few shots out, and then duck right behind it again.
Player: Okay. So she's looking through the door. What can she see?
DM: Right now all she sees is Grog and Trinket were attacking the pit fiend as it flew off, and that's all she sees now is Grog and Trinket by themselves outside on the street.
Player: Okay.
DM: And this watery sphere that's floating in space.
Player: Okay, she's going to step out of the door, and she's going to cast Spiritual Weapon.
DM: Okay, where is she going to cast it?
Player: At fourth level. If she makes it an anvil, can she knock him down to the ground?
DM: That's more of a flavor element.
Player: I want to make it barbed noose to go around his neck.
DM: Okay. In true Sarenrae fashion. All right. So for the purposes of that we will say that this glowing yellow--
Player: It's a yellow noose, so it looks spiritual.
DM: All righty. So we'll say that it's in the same space as him where you conjure it. There. At a fourth level. So at fourth level, that means its attacks do 4d8 plus five per hit. If it hits. Now that it's landed, so you cast a spell, it makes a melee attack. So go ahead and roll a d20, adding ten to that.
Player: 23?
DM: That hits, so go ahead and roll 4d8 plus five.
Player: 26 points. And is that all the bonus?
DM: That's all the bonus action.
Player: Okay, cool.
DM: She cannot cast any other spell, unless it's second level or lower.
