Ultralisks are probably the least used zerg unit in starcraft... but they have a secret power which can easily win the game for you.

for this to work you haev to get an expansion early and the more you get the better... (this works best on terran)

Zergs best abillity is its mass products and speed...

When you begin the game get drones like you would normaly and a solid anti air and ground defense... stick with only one hatchery until you at least have a lair... once you get a lair go to one maybe two expansions (and i dont mean natural expansions outside your base). you should have about 20 miners in each base maybe more like 25. then in one moment get about 10 new hatcherys in one base and key structures in another... as long as these two are seperated you are safe... by now you should have a hive and every single structure... dont forget to be upgrading the whole game (air and ground). then start producing an small army of about 12 ultralisks... they are one of if not the strongest ground unit in the game... when you have this army hide them in a corner of your base so the enemy wont realize you have them... you will need the element of surprise. next fill up your overlords (who should have all of their benefits by now) with lings that have their anderline glands updated... then make a small army of about 12-18 gaurdins but make sure that you dont have any devourers or scourge... position your overlords on one side of the enemys base and your gaurdins on the other... then move your ultras to the front. now send in your ultras MAKING VERY CAREFUL CHECK THAT YOU DO NOT SEND THEM FARTHER THAN THE DEFENSE LINE!!! BE SURE TO LEAVE THEM WHERE THE ENEMYS DEFENSE IS/WAS. ultras will make short work of anything there and the enemy will undoubtingly send wraiths and battle cruisers to kill your powerful beasts. tell your ultras to hold positing and get killed very slowely... if they have the armor upgraded this might take a while... with the destraction being taken drop your zergling into the middle of the base where the key structures should be located... the enemy will either go kill the lings or stay with the ultras... either way as soon as his/her building start blowing up send your gaurdins to finish off the command center and any scvs. if any TRY to escape the enemy is a moron cause you have lings and ultras blocking the way out. this trick takes practise because you have to move fast and react quickly and not waste time... and dont forget that without upgrading the chance for succes is limited...

oh and incase your wondering why not to build anti-ait its cause you already kicked the enemys @$$ there is absolutly no need to kill his only means of safety left. like i say crush his base not his hopes.

CreepColony's Opinion: You should definetely throw in dark swarm for your ultras.