ToME: the Tales of Maj'Eyal

I have a skeletal bulwark using Step Up at tier 5.

The skill increases move to 1000% for 1 turn, which should come to 10 steps, as I generally have no other move or speed effects on me, but after repeated tests I find that it does not allow this rate of movement.

The actual number of steps permitted seems to vary quite randomly from 1 to 10, averaging around 7?

These tests were generally run without any remaining monsters around to interfere with movement, and with no active effects on my character other than 'Shield Wall', 'Chant of Fortitude', and 'Step Up'.

There's a background turn timer that the game uses to tick down status effects, run time limits down, and things like that. Your character's personal chances to do stuff may be set in different places along the background timer. If you take your turn just after the background tick, you get your full 10 moves, if you get your turn just before, you get fewer.

Yes, that is exactly my impression - In some cases it effectively fails to activate altogether, as it pops on and off in the same tick, before you even get to move.

Basically you're stuck with %chance fail to activate (down to zero for a full 5pt skill investment), then you're stuck with an invisible 0-9 turn move timer that makes it impossible to plan your moves out carefully, and finally there's no guarantee whatsoever that an enemy won't act even while your 'fast' phase lasts, vaporizing you while you're trying not to trigger skills which would break your movement effect.

In short, your chances of actually running across the room to stun that next mage/archer before he pins/freezes/obliterates you are vanishingly close to zero, even with the skill fully specced out, which basically nullifies the skill's purpose.

At the very least the skill's description should be amended to say that it grants a random (0-1000%) speed bonus on a kill.

Truth in advertising.