[Thy_Reaper]

Add the bonus movement ability, and make the Amount1 this:
BaseBonus + iif( [%Level%] > 5 , 1 , 0) + iif( [%Level%] > 7 , 1 , 0) + iif( [%Level%] > 9 , 1 , 0)

This should give BaseBonus at levels 1-5, BB+1 at levels 6-7, BB+2 at levels 8-9, and BB+3 at level 10.