Does lightning come down from the sky or up from the ground

Yes.

It comes down from the sky, up from the ground, or both in a single bolt.

Some of the videos at the source below show bolts going in all sorts of direction. Check them out, especially the slow motion videos where you can actually see where the bolts originate and which direction they are going.

The answer is both. Cloud-to-ground lightning comes from the sky down, but the part you see comes from the ground up. A typical cloud-to-ground flash lowers a path of negative electricity (that we cannot see) towards the ground in a series of spurts. Objects on the ground generally have a positive charge. Since opposites attract, an upward streamer is sent out from the object about to be struck. When these two paths meet, a return stroke zips back up to the sky. It is the return stroke that produces the visible flash, but it all happens so fast - in about one-millionth of a second - so the human eye doesn't see the actual formation of the stroke.

There is initially a 'leader' upwards from the ground (or whatever object is being struck).

That ionises a path in the air and the main strike then comes downward.

See the link for example pictures.

Both, just before a lightening strike the air is so heavily charged that you get upstreams, where it meets a downstream you get a lightening strike.

Down from the sky

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It comes down from the sky.I