You were right in thinking shield strength is the way to go.
A lot of people complained that ISICs tank status has been destroyed, but that’s just not true. I’ve actually been a little skeptical about posting it on the forums in fear that he would receive yet another nerf.
ISIC plays a bit different than other tanks. Where most tanks rely on soaking up damage with health, ISIC relies on soaking up damage with his shield and shielding abilities.
Here’s how I play him and build him (and I may add that it’s extremely affective once you get the hang of it).
First off, I use two max shield items and 1 max health item (that stacks after 180 seconds - just incase enemies break through all of your shielding) with two shield items and his shield helix choices you eventually get close to 800 shield! That’s a ton of rechargeable damage mitigation.
Secondly, I play him similarly to Montana. You soak up a lot of damage and eventually scare enemies into retreating via slight d.o.t (your cannon).
Third, his gameplay: --1-- Start of by constantly firing your cannon and over charged shots as much as possible, letting your big ol’ shield soak up damage until it’s depleted. --2-- use your next overcharged cannon to pop up an over charged ward, then continue to fire your cannon to scare your enemies until all your wards break. --3-- at this point you’ve recharged your shield (or most of it), but don’t deploy it just yet, nows your chance to let your allies deal some damage, while you draw aggro. Get close to the enemies and pop up your aegis shield (if you’ve selected the correct helix, it will soak up 2000 damage before it breaks). --4-- rinse and repeate, while activating our overcharged ultimate with overcharged wards as much as possible (but make sure to leave it once you start taking health damage).
If you do this you will tank a ton of damage, while also eventually making many enemies retreat and even snagging a kill every now and then… all while taking almost no health damage at all.
(A health regen item or a damage reduction items also works well if you don’t want to use a max health item)