As the chapter title suggests, these are luxury items that will vary from situations to situations.
All these items are very useful in different occasions. Pick wisely depending on the opposing heroes. Practice will let you know when to use these.
At this stage of the game, your sniper should be owning and harassing the opposing teams. This is the time when sniper is very useful in pushing to finish off the opposing side.
Now at this stage of the game (mid game), it is a must to have these 3 items. It can be vary from situations to situations, I will put the other items in "luxury items" section.
Please take note that sniper is effective at far range, always stay at the back of your team or hide in the trees.
purchase these 2 items, this will give Sniper an upperhand in early 1vs1 or clash in getting the first rune.