LoL? Why you bought Atma's Impaler? 2% of your all health is very weak you know that right? With 3000HP that not justifies that Item... But ok there are opinions... About 2 Trinity Force I think that is another stupid choice...

Here are some of the gaping errors in your guide:

a second Tri Force which has a UNIQUE PASSIVE instead of an Infinity Edge?

this sion will have mana problems without Doran's ring or seals of clarity

his dps will not be v high because he doesn't have enough armour penetration

he has no magic resist. he even avoids it in the mastery tree and takes armour instead

there is nowhere close to enough detail in this guide. i can't believe it's this highly rated.

it's also just plain bad.

This build is ****in amazing i always go 20-1 or higher you do ridiculous damage i surprised its not at 90% because the items are easy to get and its absolutely a game turner

You may want now to change Malady with Stark's Fervor, cuz Malady don't steal life anymore, also Stark's Fervor decreases the enemy armor, witch is better then reducing magic resistance for your style. Also, what will you do against a heavy cc team? You'll curse those Ryze, Te Emo, Veigarar and others you meet if you don't have Banshee's Veil and/or Cleanse spell. :-?
Other then that, it is preety much like the first build i used on my Sion, worked well till i hit this wall i told you about.

update this and remove malady, worthless on sion now...phantom dancer would probly be ideal seeing your going for speed, nice build though, i dont like that you have nothing in the way of armor and magic resistance but hell with your ulti giving 100% lifesteal on top of the 25% you ahve and a 213% attack speed(263% with ulti) you may not even need the **** lol, havent tried it but plan to looks like it could be a hit or miss thing though

get a stark's fevor instead

Is malady still what you should get since the change?

I really liked this build. But now Malady has changed to not have lifesteal, and Vampire Scepter isn't a part of it
So what do you replace it with?

well done
i played ap before
but this is the first build that really reveals his dps power

u might want to change the items now because malady no longer has life steal not i has AP D:

Awesome. First time i tried it at a 4 vs 4 game - we had 2 leavers- and i had 21/12/16. Of course we won and the most amazing? Almost 122000 damage dealt ,quadra kill and 4 multi kills. Thank you meatloaf for giving me a really enjoyable game

You're right heal by itself is more or less ineffective, however because of Sion's W skill you can use it as a pinch skill. I find most times the only time I'd need to use heal would be to get a little extra health during a gank during Cannibalism's cooldown. Also a helpful tool during Cannibalism if allies are in range and hurting, sync it to Cannibalism's extra effect which can bring an ally up a fair chunk when combind.

You are right though, Flash is better for Tower Diving and escaping and ghost works in particularly the same way.

Personally I take heal on Sion alot of times because of early game, its a good way to get a FB or clear the lane of enemy champions, with Enrage active and another melee champ in the lane they tend to want to stand toe-to-toe with you. If they happen to have heal and you dont, curtins.