A shape stirs off in the gloom; a distant glimpse of yellowed bone and the hollow eye socket of a skull. The room reverberates with strange sounds as you squint hopelessly into the dark. The chattering din of iron on stone rises to a fever pitch. And then you see the wheel.
Speed 30 ft. (90 ft. charge)
Bonewheel skeletons begin combat lurking far away from the party or masked by the distraction of other undead already engaged in the battle. When an opportunity presents itself they bowl through the party's ranks with rolling charge. If their overrun is successful, they continue moving in the same direction until the end of their charge, ending their turn out of reach of melee fighters if possible. They continue to exploit their speed advantage in this manner, making hit-and-run attacks which only place them in range during their charge. While rolling they turn very slightly, providing a small amount of flexibility to their line of charge.
Bonewheels without room to pick up speed use spinup to bolster their charge attack, and aim to place themselves in safety after the ensuing overrun. If halted, blocked, or tripped such that they are caught in the melee, they will attempt to withdraw on their legs to find a better position.
Str 18, Dex 18, Con --, Int 15, Wis 14, Cha 16
A bonewheel skeleton can make a special charge attack with the spiked wheel entwined in its ribcage. As a full-round action it may target a square up to three times its speed (90 feet) from its current position, moving in a straight line towards that square and attacking any targets it strikes along the way with its slam.
If the slam attack hits, the bonewheel makes an additional secondary attack with one of its wheel spikes for each 5-foot increment it moved since the beginning of its charge, minus two for each target it has previously struck in this way, to a maximum of five.
The bonewheel automatically succeeds on an overrun maneuver versus any target it has struck with its slam, and the target must make a combat maneuver check or be knocked prone. If the target succeeds this maneuver check by less than 5, their movement speed is halved on the first move action they take on their next turn. Bonewheels may overrun creatures up to one size category bigger than themselves.
If the bonewheel's slam attack misses a target, they may choose to block its path, ending its charge and not suffering the automatic overrun, but instead receiving all of its secondary attacks and a bull rush. Alternately, they may choose to allow it to pass harmlessly through their space, receiving an attack of opportunity against it as it leaves their reach.
A bonewheel skeleton often finds itself in narrow corridors or surrounded by foes with limited avenues of attack along which to pick up speed. When caught in such a situation, it may opt to spin violently in place, gathering inertia before rocketing forward as violently as if it had been rolling across open ground.
This may be done as a full-round action, granting the bonewheel secondary attacks on its next rolling charge as if it had travelled 25 feet; as a standard action that grants 15 feet worth of attacks; or as a move action that grants 10 feet. After spinning up, the bonewheel may not move normally and must make a rolling charge on its next turn if it is able to do so. If it prevented from doing this for any reason, the extra attacks granted from spinup are lost.