Lux can make use of many runes in the Inspiration Tree, such as Perfect Timing and Biscuit Delivery. Now with First Strike, you can get extra gold as a support and put it towards your full AP Lux one-shot build!
Gangplank was known for being a fantastic 'Grasp of the Undying' user. The keystone allowed him to gain HP and poke his opponents out of lane, but it became less useful with his rework. Many GP mains still take Grasp, but this may change with introduction of First Strike - allowing you to stack gold and scale easily!
Katarina mains took notice of her insane potential with this rune by taking it into practice tool. First Strike can easily earn you 1000 gold per ult, which is just insane! Stack your money quick and get super-farmed in no time with this OP rune choice before they nerf it!
Just like Gangplank, Ezreal was a Kleptomancy user before it was removed from the game. That rune was downright OP on Ezreal, giving him so much value in return for very little risk on his part. This champ should be a huge First Strike user, since you can almost always out-range opponents and earn that extra gold!
This champion is the most obvious choice for First Strike. His low cooldowns, ridiculous range, and huge AOE's make him the perfect candidate for this keystone. This combination will almost certainly be nerfed, as you can always get huge value out of your abilities. Make sure to use this in Ranked before it gets nerfed!