With this build, your aim is not to play as a support, but as an offtank ap, that can win any 1vs1 fight, and can give your team more magic damage and free seconds to ace the enemy team.

The bad point of soraka with this build is just "removed": now, you can tank a team fight - quite easily - if you do not forget to use cleanse at right time to heal yourself while your team is killing enemies (freely because they all focus you!). If you are in a really bad position, use your Zhonya, so that your team have 2 more free seconds to kill the enemy team (because they will still focus you during those 2 seconds to kill you as fast as possible). As soon as you can, use your exhaust on the enemy who is dealing the worst damages. With this build, I have already made a lot of 1vs2 fight: I usually kill them both and I survive (this happens often). I have already aced a team alone (pentakill with no assist: this happens rarely... but it happens sometimes ^^).

Try it, and enjoy it.

IMPORTANT POINT: this build is made for team fight, much more than for fragging alone. So, if your team is losing, do not try to kill enemies under tower alone (even if you are sure you can do it)... but if you are winning, go do it and have fun :p

As this build is "offtank soraka", and to optimize the use of "primary" runes, I have chosen:
- RED: magic penetration
- YELLOW: armor per lvl -> you must play safe at beginning
- BLUE: magic resist per lvl (pure magic resist is not effective at beginning as players rarely have powerful magic damage at beginning, but is largly more important in the end, and with abyssal scepter + your passive, you will not need more magic resist).
- GOLD: movement speed (quite interesting when you use your Randuin + Rylai with Q & E, in order to make sure you can chase enemies)

As an offtank, its normal to use the "Defense tree". The others points for "running" and duration of buffs (Runic Affinity) are important and quite interesting too, especially for the blue buff that you seriously need (if possible).

The first item to purchase will help you earn gold during whole game until you buy your last item - randuin - which completes it.
The shoes chosen provides you -from start- a good CD reduction for your Q and E.
"Will of then ancients" is really powerful on soraka, during the whole game, especially when you are full stuffed. If someone else takes it, your life steal goes up to 40% instead of 20% (it can stack twice!).
Abyssal scepter provides you magic resist (your should not need more, except if there is only full AP team against you) and AP, and it reduces magic resist of nearby enemies by 20... useful to complete the magic resist reduction of your Q (so: up to -140 magic resist to all nearby enemies around you) !
Frozen heart will be very powerful to reduce attack speed of enemies around you, and reduces damage done (100 armor), and reduces your CD (--> 40% CD reduction)!
Randuin will complete Frozen heart during around 4 seconds when you use it... to finally reduce enemies attack speed by 50% and movement speed by 25%: ideal for "instant" rush -->
"instant" ACE with your team! Furthermore, it has CD reduction too!
Rylai... it provides you AP, +500 life and movement speed reduction with your Q (15%) & E (35%)!

With full stuff:
- you have max CD reduction (40%), you have a very good survivability (life steal, life regen with "Z", and with your ultimate "R")
- you can kick *** ANY enemy on 1 vs 1. This is easier if there are enemy creeps to steal life from them with Q: so run to enemy base spamming Q to kill your enemy, its easier that way, and finish him with "E": when he is around 20% life left, it's enough to use your "E" to instantly kill quite any hero thanks to magic resist reduction (around 140 after 10x"Q" + abyssal scepter) !

I am quite surprised that every guy that does not know my way to play lame on me because I farm too much (upon them, I should never farm), I do not use enough wards, I do not upgrade heal, I do not take CV... Do they know that:
1) If you do not farm, you do not havve enough money to buy wards.
2) The heal CD is about 20 sec... it really does not change a team fight whereas spamming "Q" + "E" makes much more damage and can kill, even 1v3 (I have done triple kill with no assist yesterday while I have been ganked alone on a lane...).
3) You have much more survivability with "Passive healing" from stealing life thanks to "Will of the ancients" and thanks to your armor + magic resist.
4) CV can be replaced by wards... which you can buy and place... if you farm a bit! (this is true for every hero, not only Soraka)

The enemy team will certainly focus you hard, thinking you can die very fast... if it comes up to be true (which is rare), get ready to use your "CLEANSE" + "R" instantly to make you survive then "W" on yourself, and prey for your team will ACE them :p. So: YES, cleanse is a good choice with Soraka. And exhaust too: use it on the hero that makes most of damage on you. Playing that way during team fight, you may survive, and your team will remains full life... :p
And "IF" you are in a really bad position : use your... Zhonya :D

Soon, I will publish some screenshots from my team saying, at every beginning of games:
- Stop this Soraka!
- Stop last hit!
- Go put wards!
- Stop harassing enemies!
... those guys just cant understand that they just can NOT farm cause im harassing them so much, and soraka is not a good char to farm... any AD can do it much more easier so go L2P.

5 minutes later, the same guys say:
- LET me kill them omg! (...they did no assist, so they just didnt hit them at all)
- WOW nice ! (... they just last hitted 2 enemies, while being full life full mana)
- OMG! GG! Sorry... (... i have just killed 2 enemies + the ganker = 3 alone while he just left me alone)

And comments from from enemy team:
- Go ban soraka!
- Soraka op!
- GG Soraka... your team was bad, but you... GG
- ...