When and why is it very effective to use Zhonya's Hourglass?
Yesterday I played Swain. I thought buying Zhonya's hourglass is pretty awesome on him, because of ap and armor of course, but mainly because I like to focus on the active. A pretty cool thing about it is, that when you use Zhonya's while he has his ultimate on, it stays active, which saved me very often. I was able to use Zhonya's at low health and when my Zhonya's active expired in the teamfight, I had like half hp or so.
The thing I wish to know from you guys is that which champs are good with Zhonya's and which are not, because I don't know which ultimates get interrupted by Zhonya's and which not.
Most ap champs can use Zhonya.
The ones that make the most use of it are the ones like Swain that have an ability that keeps going even when using it.
Swain, Morgana, Kennen, Fiddlestick (ults) and Karthus (defile) are the ones, of the top of my head, that have such abilities that will keep going while under Zhonya protection.
It can also be used on squeesh ap champs that use it for the protection only and that they need to be in the middle of the fight to deal the most damage, like Fizz and Katarina. It's a life saver. It may be used on Kassadin but with his escape ability, it usually not as useful. It will be seldomly used on Annie, Brand and the other ap champs that usually are not in the middle of the fight in case they get there and needs time for another cycle of spells.
Other ap champs can still use it but some don't generally use it, like Diana and Orianna. You won't see many people running Zhonya on those 2.
Any champion that has an ongoing high damage ability that deals damage over time. For example, Fiddlesticks ultimate ability allows him to teleport into a group of enemies with an area of effect damage over time attack. The weakness of this ability is that Fiddlesticks is a low-HP squishy champion. The couple seconds of invulnerability from Zhonya's allows him to deal a proportionately high amount of extra damage, often leading to multikills.