A silicon rich world with a mass between 5 and 15 Earth masses which are in a tight solar orbit, normally tide locked. There is a lot of volcanic activity, and they have thick, cloudless, blueish atmospheres of Helium.
The high temperatures and high gravity makes such worlds uninhabitable. Tidally locked worlds will have cooler night sides, though the thick atmosphere ensures that there is plenty of heat transfer happening, which can result in high winds across the terminator line.
Such worlds lack volatiles such as water.
The atmospheric pressure tends to be 3-10 atmospheres, which tends to even out the day and night side temperatures, and can have quite long days.