Heya!

Considering the upcoming release of ONE, what do you think about the new toxic mechanic? Are cards like Venerated Rotpriest good enough to see play in modern? Or is the fact that toxic doesn't work with pump spells too much of a drawback? Is The Seedcore worth playing, even if you don't have a lot of 1/1s?

I'm exited to hear what you think.

SuckassBolas, the problem with the toxic mechanic is that it does not support the playstyle of using pump spells and there are not many cards in the current spoilers that I would consider having the power level that is needed for Modern. An interesting thing is that Infect and Toxic both trigger so you could play something like Necrogen Communion, but that card is still weaker than Rancor.
There might evolve a new deck where you mix Infect and Toxic creatures together, but I'm not the best deckbuilder.

Rotpriest looks a little too weak: you usually want to use 2-3 pump spells to win the game, so it would deal 2-3 infect damage and therefore is just another Giant Growth, but people are experimenting to create a storm deck with it using Ground Rift, here is the first list I was able to find.
The Seedcore is just a worse version of Pendelhaven: it does not produce , that is needed for pumpspells and we are already running 4 colourless lands with Inkmoth Nexus.

Maybe some of the Proliferate-Cards and cards where the opponent gets a poison counter might be playable, looking at Infectious Inuiry and Whispers of the Dross.

I'm still happy that the fastlands get reprinted and now can be played in Pioneer and The Mycosynth Gardens will probably become a modern staple.

Hope my 2 Cents are helpful :)