catalyst the protector I choose this item at start because you win level very quikly in dominion and it allow you to stay on bot lane a lot of time.

Rod of Ages I rush this item because a soon as you get it as soon it will full stack.

Ionian Boots of Lucidity Because i love -15% CD reduction for Ice Blast often.

Warmog's Armor Nunu is the champion who have the more heath lvl 18 but a warmog can help you a lot.

The rest of build should be Mr because you have only 34 without Negatron Cloak
You can also rush Thornmail if there are too mush ad champ.

Magic penetration and ap should give you good dmg with Ice Blast and later Absolute Zero

+3% movement speed because i take Ionian Boots of Lucidity and no Mobility Boots

In seals, armor is good but maybe dodge is better.

I choose a defensive masterie for stay alive a maximum of time and in offense for magic penetration.

R>E>W>Q

Promote For push the bot lane. Remember to use Blood Boil on super minion if there aren't allies with you.

Ghost For flee or help teammates ...