If you find yourself wondering why your ADC has zero CS at 17 minutes, hold your flame back. Chances are he's probably playing Senna and exploiting the new changes to her soul drops. We'll try to explain this new playstyle to every confused summoner out there.
After her release, Senna was extremely popular on the Attack-Damage Carry role and it's safe to say that, if played correctly, she was pretty broken. In patch 10.3 Riot lowered her Mist Wraith (also known as souls) drop chances for minions and monsters she kills (previously: 20 per cent for minions, 100 per cent for canon minions) to a microscopic 1.67 per cent.
By doing so they gave ADC Senna a huge nerf while trying to keep her support capabilities untouched. We have to point out that her soul drop percentage for minions and monsters slain by her allies is still pretty big:
- Minions and lesser monsters - 25 per cent soul drop chance
- Champions, large monsters, and canon minions - 100 per cent soul drop chance
Stacking Mists grants her: range, attack damage, critical chance and life steal. Every soul she gets is worth approximately 54 gold. Zven from Cloud9 got 80 souls by the 20 minute mark of the game against Immortals and that's roughly 5.4K of gold that only she is able to harvest. In addition to that, her extremely long range enables her poke and therefore makes the support item quest a pretty easy one to finish.
Also, an important thing to mention is that the support that Senna is paired with benefits immensely from this playstyle since he's the one taking all the farm and by doing so his item spikes naturally come in much earlier. She's usually partnered with supports that provide good peel like Tham Kench or Taric but that isn't a must as we witnessed in EG's win over Golden Guardians where Zeyzal did a rather solid job of playing "support" as Rumble.
Even though this new "Fasting Senna" - as she was named by the LCK casters - is pretty strong, the style has some downsides like limited objective control, hard wave management and slow tempo on lane swaps. Since the pick is conditional and requires being played around, you should probably use it in high elo or in a group of five.