But about Dumbledore having the cloak to do whatever he want to do, Why he wanted it if he can become invisible without an invisiblity cloak?

@MohammedAlhanafi That is also mentioned in the book. He wanted the clock only to examine it since he suspected it was a Hallow. I will edit my answer to include quote from the book.

So Dumbledore is powerful wizard (or most powerful), why he didn't make his own most powerful wand?

@MohammedAlhanafi That's not the point at all. Dumbledore never wanted to be possessor of Hallows to be invincible or defeat death, not even when he was 17 and dreamed about Hallows with Grindelwald. He was perfectly okay with dying and had even planned it a year before his death along with Snape.

I think i asked my last question about dumbledore making his own wand wrong, i mean by this question anyone (dangerous wizard or like voldemort) can make his own wand and make it more powerful than any other wand. but thanks for the answers.

@MohammedAlhanafi ok. I got your question. But being the most powerful wizard does not mean you know everything. Wandlore is a branch of magic which needs to be studied, not everyone knows about it. Even Voldemort who was most powerful dark wizard of his time knew nothing about wand making as it is very clear from the last book.

@MohammedAlhanafi - Just because he could cast such a powerful disillusionment charm at the time that the books take place doesn't mean that he was able to cast it at the time that he borrowed the cloak from James. Indeed, it's possible that it was through the study of the cloak that he was able to perfect his disillusionment charm. OTOH, IMO it's more likely that he simply borrowed the cloak to satisfy his curiosity about it.

Harry could come back not just because Voldemort killed a soul-speck. The fact that Harry's blood was used to revive Voldemort was a key factor. In Rowling-esque fashion, Voldemort somehow made himself a partial pseudo-horcrux for Harry (Books 4 and 7).

Also, it probably helped that Voldy was using a wand that "belonged" to Harry

I believe it was in the 4th book that Mad-Eye mentioned how everyone in class could point their wands at him and say Avada Kadavra and he would only get a nose bleed because they wouldn't have the intent/power to back it up. Going with Arcanist Lupus's comment, it could be the wand wouldn't kill its TRUE owner, and kinda botched the killing curse for Voldemort.

Spot on. The 'master of death' thing was only ever part of the mystique of the Hallows, passed on by enthusiasts like Xenophilus Lovegood. They didn't actually make one immortal.

Besides, if becoming "Master of Death" meant immortality or equated to the ability to come back from the dead - why would ol' Voldy stop at just finding the Elder Wand? Don't you think he would search out the other two Deathly Hallows with the same/greater vigor that he invested in his faith of each Horcrux? the Sorcerer's Stone? the bones of his father, flesh of his servant, blood of the enemy?

@OhBeWise - Voldemort didn't know about the other Hallows.

@ChrisDunaway IIRC Ron knew about the hallows because it's some kind of child tale.

@DanielJour Both Ron and Hermione knew "The tale of three Brothers" from where these Hallows came, but neither of them knew they were real and called Hallows until Lovegood told them about it.

It's been a long time since I read the books, but I stand corrected: It appears Voldemort didn't know about the Hallows. (1, 2, 3) It's suggested by Dumbledore that even if Voldy had known, he'd not have cared for the other two. People argue, "The other two were useless to him." Alone, yeah. I mean, maybe he could use the cloak to further protect Nagini. But if he understood the implications of having the whole set, why wouldn't he want it?

As a note, although this answer is correct, Harry did have all of the Hallows, the resurrection stone being a part of the ring given to him by Dumbledore. It doesn't change the answer, but it is worthy of note.

@Anoplexian - Did Harry ever have the ring? Dumbledore bequeathed to him the golden snitch which had the resurrection stone inside, but I don't remember Harry possessing the ring.

@ChrisDunaway Actually, I think you may be right but I'm not sure. I believe he had it at one point, but that it had not contained the resurrection stone or perhaps a horcrux? I'm not sure, I may be mixing my recollection of the movie with that of the books. Regardless, he did have all 3 at once making him the "Master of Death", but that wasn't why he wasn't killed.

This answer is mostly right, but I'd argue misses the main point: Harry's not dead. Dumbledore is. No one comes back from the dead in HP. Thus all the effort to avoid death in the first place.