[kirbwarrior]

My rule of thumb is 'what is the simplest answer?'. If you try to teleport somewhere you can't go and still succeed the roll, nothing happens. No downside, no upside, you just don't go anywhere. That's what I've done, but one player liked the idea of 'close enough' and that feature makes it so they teleport close to where they wanted to go. It was usually in a straight line (you teleport only 9 hexes instead of 10) but if the destination was really far I'd just choose somewhere close enough or roll for direction so I don't have to 'draw' the line.

Blind being able to hurt you in some manner sounds like a (very antagonistic) limitation on Warp. Small damage on a success somewhere you can't go sounds like a fine -5% limitation. Castling is a whole build of its own.