Another practice puzzle for the Keller round. This one has a wart, I messed up the sign on the break-in, and don’t see a nice way to fix it. This will have to do. I don’t remember whether it’s actually difficult, beyond the awkwardness of the type.
EDIT: Fixed an ambiguity, thanks uvo.
Rules The left grid is a Sternenhimmel. Place some stars in empty cells, such that every arrow points at at least one star, and such that every star is pointed at by at least one arrow. Clues outside the grid indicate the number of stars in the row or column. The right grid is a Magnets grid. Place + and – in some cells, such that every 2×1-plate is either completely empty/shaded (neutral), or has one + and one – (charged). Same signs can’t be adjacent.
The grids interact: Stars may only be placed over charged plates. Arrows over charged cells are rotated (90˚ clockwise for +, counterclockwise for -).
Maybe Puzzles 
It literally took me hours to finish this puzzle, even though in the end I didn’t need any trial and error at all. This seems to be one of the puzzle types I simply do not “get”. (I didn’t finish the one during the competition.)
It seems to me the domino at R23C1 isn’t determined, it can be either charged or neutral.
Thanks, I believe moving the 2 magnets clue from row three up by one fixes this.
The one on the competition didn’t seem that bad, but I didn’t quite manage to get it out in time.