During a combat that takes place on top of a moving vehicle (let's say a bus moving at 60 feet per round), What happens if you use the spell blink?
The blink spell description states that:
At the start of your next turn, and when the spell ends if you are on the Ethereal Plane, you return to an unoccupied space of your choice that you can see within 10 feet of the space you vanished from.
What reference plane would we use to determine "the space you vanished from"? Would it be:
- relative to the bus – in which case you'd reappear near the same spot on the bus, but 60 feet forward, due to the bus' motion?
- relative to the world at large – in which case you'd reappear 60 feet behind the bus?
Best Answer
Keep the PC's Position Relative to the Battlefield
(which might be the bus top)
As is common: this is a DM call. Also, we have justification for either method. The rules say: "every location on (the prime material plane) has a corresponding location on the Ethereal Plane", so the top of the bus likely still exists in the ethereal.
According to previous canon, structures (like a bus) were usually represented as gray objects in the ethereal plane, which you could move through if desired, but you usually remained 'standing' on the (ghostly) floor that you were previously standing on (even though you might be standing on an object moving rapidly through space, like a planet)
However, this is probably more of a "frame of reference" issue, so it is also reasonable to view that the bus could continue without you (even if you were inside, since you can easily move through walls). Also, blink says "you return to an unoccupied space of your choice that you can see within 10 feet of the space you vanished from", which again seems to make it a frame of reference issue. It probably wouldn't be questioned if you were inside a floating castle, but the frame of reference on top of a moving bus is more subjective.
Ultimately, it's often best keep the PC's position relative to the battlefield similar to up-voted answers here:
So if the bus is moving around on a battlemap, it's probably not the battlefield. But if the bus is the battlemap, your players might have certain expectations.
For precedence, published adventures typically treat large moving environments the same as static environments (for the purpose of casting glyphs and such). But these are typically larger than a bus. Examples:
Alternately, I might let the player make a skill roll (like Arcana) to decide for themselves.