Will Spear of Shojin gut Singed?

Spear of Shojin currently reduces damage from attacks and abilities by 10 + 15% bonus AD. For DOTs, it will be reduced to 30% effectiveness: 3 + 4.5% bonus AD. When the passive activates (need to be near 3 enemy champions), it is increased by 200% for 6 seconds.

Assuming a late game scenario, someone like Zed could get to 300 bonus AD, which would result in 16.5 damage removed per tick. This would increase to 49.5 damage when the passive activates.

The problem here is poison trail has low damage but it ticks every 0.25 seconds. Assuming defensive runes, if Singed builds no AP items, he will do 15 damage per tick, which will be completely mitigated. If we go for the standard Rylai's + Liandry's, he'll do 32 damage per tick, meaning he'll do about half after reduction in a 1 v 1, but still do none in a teamfight. If he ults, the damage prior to resistances increases to 40.5.

There are other DoT champs that will suffer, but none are as reliant on one ability for damage as Singed is. I don't even know if this is how it'll end up working, but it will severely cripple frequently ticking DoTs if it does work like this.