Just make the Last Whisper line into "big ticket" core AD items.

One reason tanks are so dominant right now is because no one is building right now, not even marksmen. Often times this is because the first marksman to build the item is going to fall behind in damage against squishies and likely lose the ability to even duel the enemy marksman because the items are useless against squishies. I don't think it's necessary to increase the % pen on these items though to make them more appealing. I think all that needs to be done is just increase their price, the AD they give and give them some other appealing stat like life steal.

Lets look at an overloaded item like

It has 75 AD 10% life steal 35 MR and one of the best item actives in the game.

If Mercurial is allowed to have all that in one item, why cant and have like 70 AD 10% life steal and its passive?

Some example numbers:

same price and build path but 30 AD instead of 25 AD.

and increase price to over 3000g add to their build path, give them 65-70 AD.

If these items had these stats would you be more compelled to build them?