What stops you from doing Russian dolls is the deployment rules for the Tyrannocyte, which MUST enter play using the DS rule. However, you can totally put the Sporecyst in one, which I find is actually a very usable option. The 10 blasts that combo puts out is crazy! Templates go flying everywhere. And the spore mine clusters are actually very effective when you are so close you can plop them right next to the enemy. lol I sent a big spore mine from the Sporecyst right into the Swarmlord XD Sorry buddy, Blade Parry only works on weapons with the Melee rule muahahaha!
The question of how on earth you can ever manage a charge on a flyer with slow spore mines was one that made me doubt their effectiveness, right up until I actually played. It was a Nid on Nid slug fest featuring Toxicrenes, Tyrannocytes, a Sporecyst, and big spores. By the end of turn two, the half of the board we were engaging on became one gigantic parking lot. I had taken two big spores as troops to grab a second force org, and I deployed them with my main gun blob on a flank. By turn 3, my opponent's Flyrant ended up right next to my mines because that was the only place he could really go. I charged in with both, lost one to overwatch, and smacked off a wound with the other. When you step back and think about it, most of the flyers need to be pointing at you in order to fire, and they have to move a minimum distance to stay flying, which means they often end up right in your face, making it fairly easy to get a charge off, or they may very well act as a deterrent to putting flyers anywhere close to you.
My Toxicrene ran up the middle and was a little bit of a bother but ended up getting charged by the swarmlord with two guard. He managed to smack a guard and a half off with the help of acid blood as he lost all of his wounds to the Bonesabers. My opponent's Toxicrene was tough to deal with since he also had two podding dakkafexes, a mawloc, and 15 podding devilgants that all came in on turn 2. He was crashing through my line with all his scary 2+ poison and his ID hits. I was hurting pretty bad by the end of the game. The only thing that saved me was my pair of dakka flyrants. They were able to fly around and deal crazy damage to all of his units while he ground down my gun line.
What I liked about it was that we both had two fairly different lists and ended up with a very close game. We had a blast playing with all the new toys and I am very happy to see what has come out. Redoing my Tyranids is officially my next project after I finish making my all tree Wood Elf army.