I remember my first time ever seeing a Sion in ranked. He really inspired this build along with my sudden urge to play this champion. He seemed quite dumb, playing him at first and seeing him played before at low levels. I always thought, along with many other underplayed champs, "He's got to have something that makes him great, or at least a build!" Now you have stumbled upon that build.

HEAL: Do not use heal as Sion. You have your ultimate, come on.
IGNITE: Ignite isn't good for jungling (In my opinion).
TELEPORT: Not terrible, use if you need to defend lanes easier.
REVIVE: No, just no. Don't try to be Karthus.
SMITE: Yes, unless you happen to like to jungle without smite..
BARRIER: Not terrible. You won't need it when you have your ultimate.
CLAIRVOYANCE: Just, don't even use it. You know why.
CLARITY: Not really bad, but not needed. You have your E.
CLEANSE: Not with Sion jungle. A not needed.
EXHAUST: Actually, this can work, if you can get close enough.
FLASH: Flash is fine, but I never liked it to gank with Sion.
GHOST: YES, MUST HAVE. Run into lane like Usain Bolt and Q them. INSTA DEATH.
GARRISON: No.

Q: Your Q is named, "Cryptic Gaze". This ability is amazing, yet doesn't need to be maxed. Basically speaking, it fires a lock on which then stuns the target.

W: Your W is a shield, that you can reactivate to explode after a certain time period.

E: The E, which is amazing, adds a certain amount of AD on when activated. But, it also takes health to attack. Each last-hit with your E on adds maximum health.

R: Your R is ridiculous and undersung. Basically, it gives you a lot of attack speed, AND lifesteal. INVINCIBILITY IS YOURS.

Pros for Sion:
1. Sion has the ability to burst down champions with E.
2. E gives maximum HP.
3. Q Stuns and gives gankability.
4. W is a shield, which does damage.
5. R gives 50% Lifesteal at level 1.
CONS:
1. E takes HP.
2. No real escape, like Fiora.
3. Not a whole lot of CC.
4. Q is only real good gank idea.

Farming is quite important to Sion.
1. Do not last hit with smite, last hit with E.
2. Use E to last hit everything.
3. Keep ahead in farm by a lot.
4. Turn W on before farming to take less damage.
5. If you want, use R to solo dragon earlier on.

Sion is crucial in ganks.
1. Make sure bushes are not warded.
2. Go in with Ghost, and then Q them.
Team Fights.
1. Go in after your tank, and turn on R.
2. Weaken them before dying.

Masteries are up to you.
1. I use a lot of AD, because I like early game easiness.
2. Tanky masteries work, I usually don't use them though, on Sion.
3. Sion doesn't truly need AD masteries, tank ones work well also. AD is just nice to have.

RUNES are up to you. This is how I like mine.
1. Lifesteal, E takes Hp.
2. Armor penetration, you need to penetrate their armor. I look up to Taric for this one.
3. Magic resist, we don't need Taric penetrating our armor.
4. Armor, don't let them penetrate you. Especially Kog'Maw. He's a creep.