There are a few things you might want to take into consideration. Crit Damage runes are worse than almost any other rune for damage output (including Crit chance until very late game). The increase in damage from Havoc (21st point in offense) only increases your base damage by 5% so that is maybe 5 extra damage at level 18. Heal as a summoner spell is very strong early game, but nearly useless late game. The item build is alright, but you have 30 MR. Unless you have totally perfect usage of Alpha Strike to dodge CC and Meditate to pump your MR up for the big nukes, you are just going to get destroyed by any AP nuker when they knock your MR to 0 or lower.