Zilean is the most versatile champion in the game!
In Poke Comp, Zilean In Siege Comp, Zilean In Standard Comp, Zilean
In Mid Zilean In Support Zilean In ADC Zilean In Top Zilean In JG...Prolly Not Zilean
The more I play this champ with a kit that is 'outdated' I see more and more that it fits into literally any comp, he is like a Zoe but with a little less kill pressure and a little more team utility, hitting double bombs stunning multiple ppl and doing very very nice burst dmg mid - late is so rewarding; getting a clutch utility off in a fight is already well know but taking aery and just hitting E on someone can get a clutch mini-shield burst o speed that could possible save someone from death.
Setting up engages with speed bomb plays and getting kills when you were already walking away #Stylin'
That isn't to say he is the 'best' champ in the game but the more i play this champ the more i feel he is very underrated. Scales pretty hard core, can combo off of any engage insanely well, can start off fights from ranged pretty easily and yeah he is pretty fun to play after a while.
On Monday, Zilean Tuesday, Zilean Thursday, Zilean Friday, Zilean Saturday, Zilean
and Monday we do it all over again!
(after 6)
(while ally is around)
(while ally is around)
.
Those champ seem to be able to do almost everything without excell too well on them (despite getting overbuff obv).
Karma especially is very well know for having 3 standard setup (Tank,Poke Mage,Enchanter) + some kind of variation like Ap battlemage and really sometime on hit mage (Ult Cd) but the last is really rare.
Other 2 example could be 
and 
they do not need to swap items to fit the current strategy which makes them extremely versatile
Kennen just have t prioritize different spell and type of play
Heimer just have to change the configuration of his turret
to split push) or some (as fiddlesticks) are just really not good at the other things