I have. I thought very hard about it T2. Assimilate is a very large tempo loss, which against Mono black, let alone Nightmare is very hard to comeback from, in addition to this its atech slot, and hitting that tech 1 on T3 is important. Given I didn’t know if he was going to play it T2 (I suspected it was likely, but he may have had it T1, but not want to play it for fear of being blown out) and if it didnt see play, assimilate is a dead card in hand. Plus If I want to build tech 2 of T4 (and I REALLY want to) then I can only play it T3, and then it also means I can’t play a 3 drop of T4 with the Tech 2. Its a really hard call to make, as it turns out I couldn’t tech 2 on 4 either becuase I didn’t float a gold T3 (becuase I didn’t float a gold, T1/2, becuase I played 3 $2 drops rather than mox + $2 drop, but then I dont have the pressure, but I do have slightly more attrition power…)
Anyway, there are some of the ramblings that I had going through my head, I haven’t had enough games against nightmare as purple to really know, It has one of the hardest starters for purple to deal with, combined with incredibly powerful T1 play which really hinders purple recovery, and its punching power at Tech 2 rivals Present, and if you can deny Purple it’s tech 2, purple is in a really bad state.
As P1 I think I need to find a way to get $1 more out of the early game here, so I can get that T4 tech 2, and then I stand a much better chance, As P2, I’ve got a few ideas, but that is looking really scary…
EDIT: People have this view that Assimilate is the ultimate counter to Upgrades/Buildings, its not. In many cases I would much prefer Nature Reclaims. If I can’t make good use of the building (say a Garrison when I’m going Present, a Graveyard etc) then its strictly worse, It costs more gold, it doesn’t remove itself from my cycling, Its hero is less impactful on the board, and if they destroy the building/upgrade, then I have to once again cycle into the assimilate. Sure in the few cases where you can make good use of the upgrade/building (Training grounds, Garrison as Past/Forecast spam, MoLaC, Battle suits [5/4 Argonauts anyone?] etc) then its better, but often it’s worse.