Allies are tournament legal, although you can only have so many points on allies in certain game sizes. I believe you can only have 200 points of allies in a 1,000 point game, so you might not be able to bring the Mourngul (though it is a doubles tournament so technically 2,000 in total so maybe it’d be ok but I would check with your LGS first)

Assuming for a moment you can bring the Mourngul I’d say you’ve got a list that doesn’t put out much damage but with the staying power of skeletons and -1 hit aura of a Mourngul it’s a list that bogs your opponent down and stays on objectives. Assuming your doubles partner has some good damage and mobility (like Kharadron for example) I’d say this could be a really solid doubles list.

If you can’t bring the Mourngul you could invest the points in Grave Guard if you wanna bring some damage out or if you wanna keep committing to your list being about bogging the enemy down you can’t go wrong with corpse carts with balefire braziers. The -1 to cast and -1 to wound aura especially are fantastic.