Hello, I'm FireRebel(TakinTheHeat) and this is my guide to playing Annie on Dominion. I decided to make a guide after I saw there were none that played Annie to her strengths for Dominion.

Annie isn't considered a great pick by many on Dominion, and for decent reasons. However, most of the negatives about Annie can be turned into positives with the right build.

Pros

High Burst

Surprisingly high DPS after initial burst with high levels of cool down reduction
Your Disintegrate = 2.4 second cool down. Incinerate = 4.8 second cooldown

Nearly permanent 50 armor and magic resist with max cool down reduction. Molten Shield has an 18 second cool down, and a 15 second duration.

Can clear entire waves with one cast of Incinerate, and last hits very well with Disintegrate

Once you kill someone with your Summon: Tibbers, you can make him chase them around for surprisingly high damage and of course, disrupt them from capturing.

Cons

High cool downs without items. This is no joke, she isn't so useful with Summon: Tibbers on cooldown, and there isn't a blue buff on this map to help cope with that. However, I tailored this build to get max cdr VERY early in the game, so your 120 second cool down goes to 72 seconds, which is much much more manageable.

Unfortunately, quite squishy. This is natural of any mage, but you aren't one with many escapes. This is countered somewhat by Rylai's Crystal Scepter but still.

This is debatable. I love going bottom, because it takes two or more tanky champions to get me off my own tower, and your burst will allow you to take theirs many times. Not only is this very beneficial to your team, but when I do well bot, I end games with 3k+ more gold than anyone else in the game. If you can farm bot, you will be beyond fed. The minions give you so much gold.

You can also go top. Your stun is very valuable, as is your ranged nuking. I feel that Annie is a good enough defender to go bot, and getting Deathfire Grasp, Rylai's Crystal Scepter, and Ionian Boots of Lucidity is extremely important. Going bot lets you do this much faster than you would picking up the odd kill at top.

Greater Mark of Magic Penetration - Nothing possibly better for this slot
Greater Seal of Vitality - You will have a near permanent +50 mr and armor from max cdr molten shield so hp per level is really good for this slot. I wouldn't take anything else, but viable alternatives are mana regen, armor per level, flat armor, or mana regen per level.
Greater Glyph of Scaling Ability Power - Don't need cdr because of our build, so these are best in slot. Alternatively you could take magic penetration, Magic resist, or flat ap(highly recommend against).
Greater Quintessence of Movement Speed - Annie's base movespeed is pretty low, and this with the Swiftness gives you a little more elbow room.

I start with Boots + Prospector's Ring. This is really up to the player.

After that is decided, you want your Ionian Boots of Lucidity the next time you go back. You need to kickstart your CDR, and the extra move speed is great.

Your next priority will be Deathfire Grasp. This will give you some decent AP, and some mana regen, which is unneeded, to be straight with you. The biggest thing about this item, is its amazing 15% cool down reduction stat. This item maxes out your CDR and makes you really hard to deal with. 72 second tibbers, 2.4 second Q, 4.8 second W, permanently up molten shield. This item completes the core.

Start work on your Rylai's Crystal Scepter This makes ALL of your spells slow. If someone auto attacks you with E on, it slows them. If you are chasing a runner with Q, it slows for a massive 35%. It gives a nice 104 ap with the deathcap multiplier, and a huge 500 health. Much needed.

Now, you need that huge burst. The Rabadon's Deathcap, of course. This item doubles your damage. It is absolutely amazing.

Finish off your build with an AP defence item such as Abyssal Mask or Zhonya's Hourglass

Void Staff before/after abyssal/zhonyas depending on how your enemies are building.

Abilities

You want damage, not defense. Disintegrate has the lowest cooldown, it has the lowest mana cost, and does the most dps. Its great for last hitting. Max first.

Next comes Incinerate. Again, we want massive bursts to kill people and take their points.

You will max Molten Shield last. Do not underestimate this skill. Its a free 50 armor and magic resist, and also deals damage to pesky auto attackers like Yi. With max CDR, this skill will have an 18 second cooldown and 15 second duration.

Your ultimate, Summon: Tibbers is a godsend. It tops off your burst combo and gives you an annoying interrupting minion to send at people who sit on their towers. You put a point in this whenever possible.

Ghost and Flash. There aren't many exceptions to this. You can take Flash and Ignite, but I don't see the reasoning if you can just ghost and stay in range to land more spells and stuns. Annie is extremely immobile and these are the best spells in the game to counter that. You can kite with both of these spells, you can attack and burst with both of these spells. They are by far the most flexible and useful of the summoner spells, for a mage, in my opinion.