18... H(1,6)
Chess on an Infinite Plane (hitthepin - Bad_Dobby_Fischer)

Interesting question. I’m still not really sure. Technically the nominal values are 6 for the hawk and 9 for the chancellor. But the Hawk is extremely powerful in the opening, whereas the chancellor needs open files and an endgame to be truly powerful. Most Chess on an infinite Plane games do not reach the endgame, however. So it’s up for debate.
Why do you ask? I don’t see any chancellor forks or anything.

There is a discussion of piece values for infinite chess (here).

Wait, hold on. I cannot move any pawn to (-4,-12). I meant to play 20... (-4,12). Also, I do not have a piece on (-4,12) to be captured. Do you want to go from 20... (-4,-12)?
Wait, hold on. I cannot move any pawn to (-4,-12). I meant to play 20... (-4,12). Also, I do not have a piece on (-4,12) to be captured. Do you want to go from 20... (-4,-12)?
im capturing your pawn

There is still a problem. The (black) pawn on the -4th file can move one or two squares. So it's either:
20....(-4,14) <moves one square>
20....(-4,13) <moves two squares>
(remember the rank above the blue line is rank 9, so you can count from there).
Once hitthepin specifies a legal pawn move, Bad_Dobby will specify his move.
17.H(8,-3)...H(4,9)
18.H(8,0)