Tiles Diagonal to + are safe. Group 1 NW / Group 2 SE
Locate the marker not in a corner-- the safe spot will be a middle square 2 tiles away.
2 of the markers are in the same quadrant. Safe spot 1 is the middle tile closest to them, and safe spot 2 is diagonal to 1.
Checkerboard pattern.
Two patterns:
Short tether: Safe spot is 2 tiles away from the tethered corner. Choose the approprate spot to dodge Ixou.
Long tether: Safe spot is 1 tile away. Choose the approprate spot to dodge Ixou.
Safe spot is in the corners of either an untethered middle +, or a tethered middle X. 4 safe spots
Look at the two diagonal tiles between corner + tiles, then eliminate one of them based on the 1 non-corner shape.
Same as first-- easy.