UNIQUE – GIANT SLAYER: Grants up to +15% physical damage against enemy champions with greater maximum Health than you (+1.5% damage per 50 Health difference, maxing at 500 Health difference).
when i read this i just think why i should buy health and hurt myself by getting 15 % extra damaged ?
Because you're a tank and you have to buy hit points or a breeze will kill you. Wait play a mage instead. Just don't build some of the hp ap items even though some may be core to the situation. On second thought play as a support and don't build sightstone and locket. Wait im err... Riot is more than likely will tweak it.
Best suggestion I've heard from the player base is make it start giving damage after the target has 3000 hp. Supports don't go that high, maybe tank supports. And mages barely brush it. Tanks need more than that much hp at least and same with juggernauts and bruisers if they're expected to survive the front line.
You won't have any choice! Your base HP will be higher than the ADC's base HP anyway! MWAHAHAHA.
The idea is that the damage increase from the old Last Whisper was at a fairly good place against tanks.
The change to LW - only affecting bonus armour - means that it is much weaker. The change is good - there was little reason for LW to be an effective purchase against all targets - but something extra had to be added to keep tanks in line. Enter Giant Slayer. Now, this still increases damage against squishier targets by a similar amount depending on item builds and level difference. However. What it does is it means that if a champion gets ahead, Giant slayer doesn't help their damage against squishy targets. And the most important point: It also means that there is an additional balance lever. Simply increasing or decreasing the number "500" or adding a flat health threshold will have a big impact on the power of the item against squishies - something that LW did not have.
Remember that this is the preseason. We expect everything to be awful balance wise. There is time to fix it if it needs to be fixed - don't worry.
