When Jeren first saw the small figure moving slowly ahead of him across the sands, he’d given it little thought. His mind was occupied with thoughts of the Tournament—and his revenge.
Then he had drawn closer—the figure was moving much slower than he—and realized it was a young boy. He couldn’t help but wonder for a moment what a child would be doing wandering the wasteland alone.
He was considering which spell he’d use to end the life of his brother’s murderer when the boy, who was now only a little ahead of him, swayed and then collapsed onto the sand.
Jeren reached the boy in a few long strides. He knelt down beside the motionless body, cursing his luck. He’d wanted to arrive at Deleif Retep early for the tournament, so he could assess his opponents.

Second version

When Jeren first saw the small figure moving slowly ahead of him across the sands, he’d given it little thought. His mind was occupied with thoughts of the Tournament—and his revenge.
He was considering which spell he’d use to end the life of his brother’s murderer when the figure, which he now realized was a young boy, swayed and then collapsed onto the sand.
Jeren reached the boy in a few long strides. He knelt down beside the motionless body, cursing his luck. He’d wanted to arrive at Deleif Retep early for the tournament, so he could assess his opponents. But his conscience wouldn’t allow him to leave a child in the wasteland to die.
The boy looked about twelve beneath the coating of sand and dust that covered his body. Jeren pulled out a skin and dribbled water onto the child’s parched and swollen lips.

I like the title. It conjours up interesting images.

You have three things happening, one is the collapsing child. The other two are in his head; the tournament and his revenge. I think that one of the thoughts has to go for the moment for clarity's sake. (Or maybe not, see my second idea!) I don't know which it would be easier to cut, but although they might be linked in the back story, they seem separate to me.

The sentence, "He was considering which spell..." stands out as a clunky subject change, but if you could use it as the first sentence (with some tweaking) it might make a good hook. As it is, the switching between ideas didn't quite work for me.

The setting is a wasteland with sand. If you trimmed one concept (revenge or tournament), you could maybe give more sensual detail - is it hot? Does it smell? What time of day is it? Is it Earth, etc.

Second idea:

Or, having thought more about it, (!) if you cut this para, "Then he had drawn closer—the figure was moving much slower than he—and realized it was a young boy. He couldn’t help but wonder for a moment what a child would be doing wandering the wasteland alone," the thoughts carry on pretty smoothly. You would cut the paragraph break too, as so:

When Jeren first saw the small figure moving slowly ahead of him across the sands, he’d given it little thought. His mind was occupied with thoughts of the Tournament—and his revenge. He was considering which spell he’d use to end the life of his brother’s murderer when the boy, who was now only a little ahead of him, swayed and then collapsed onto the sand.

Hope this is of some help.

I like the second set of suggestions, I think I will try a new version... As far as the two seperate thoughts...maybe it isn't clear but the revenge and the tournament are connected...he plans to get his revenge at the tournament.

Oh and thanks Meredith for the offer. I'll send it along when its done.

This is pretty good, but I see a few bits of tidying up which, in my opinion, would improve it. By focusing on what is happening to the guy now you will be able to use more of your 13 lines to create a greater sense of immediacy--which is more engaging.

1) I don't think you need mention the revenge and the brother's murderer as it dilutes the hook you created around the young boys predicament. Presumably when you arrive at the tournement you will have ample opportunity to get in those details--and they will feel more natural (conversation with another person at the tournament--the boy perhaps).

2)...But his conscience wouldn’t allow him to leave a child in the wasteland to die.

I think his actions say this and therefore this sentence is redundant. You could use the words you save to put in something else in your intro to increase or sharpen the hook...

3) Could he tell it was a young boy rather than a young girl from behind? If so, how? Anyway he will find out when he rushes forward--so why not wait until then?

4) ...coating of sand and dust that covered...A little redundant, IMO. ...sand and dust that covered...or ...the coating of sand and dust...
e.g:

When Jeren first saw the small figure moving slowly ahead of him across the sands, he’d given it little thought. His mind was occupied with thoughts of the Tournament.
He was considering which spell he’d use when the child swayed, then collapsed onto the sand.
Jeren reached the boy in a few long strides. He’d wanted to arrive at Deleif Retep early for the tournament, so he could assess his opponents...He knelt down beside the motionless body, cursing his luck.
The boy looked twelve beneath the sand and dust that covered his body. Jeren pulled out a skin and dribbled water onto the child’s parched and swollen lips.

I liked the thoughts of revenge, his brother's murder and being early to size up his opponents. It shows how distracted the MC is on his journey.

I didn't think it was clumsy, because, in my mind, the style matches the MC's thoughts. It's a nice juxtaposition, thinking in relatively dark terms, then having to reluctantly soften things up because of the boy.

I'd certainly be hooked enough.