but to get 100% hp increase you have to be near 3 enemies or more...
and if a big slow massive tank is in the middle of 3 or more enemies why arent people using CC/exhaust , kiting him etc
and
active has a 90 sec cd ,
has a 300 sec cd
so the interaction of the 100% hp increase being active with the 90 sec cd with the 300 sec cd of his flash and
90 sec cd ...and the cd of his ult all has to be timed perfectly in a perfect storm to have 100% effectiveness.
also his stacks are limited only 6 stacks can be obtained from minions and non epic monsters so anything beyond 6 stacks has to be a champion kill or a epic monster kill ( drag, baron, rift )
also if his ult can kill a target there is a red ring under neath that target ... so it indicates that what target/enemy can be executed by cho's ult.
oh and the kicker on all this is his ULT is melee range... yes it increases on stacks but is limited to 10
so there are alot of what ifs that have to happen for him to pull of this ideal perfect 1000+ true damage ult ... and its not common.
if you look at the break down of his average damage per game , 60% of his damage is magic damage, only 22% of his damage comes from true damage