Death QI is 6.3. Water QI is 6.75. Hm.. if you want more consistency, go with Pendulums instead of two different kinds of Towers. Chances are you won't draw Sapphire Towers, which means those Crawlers will clog up your hand along with the Aflatoxins you can't pay for yet and the shields you don't need. 4 Skull Bucklers are enough, although I would rather use Permafrost Shields to stop the enemy's creatures and buy time. That works better with pendulums as well.
I will note that in a stall, Physalia are quite enough to take someone down, though, and even Deadly Poisons are more consistent than those Crawlers. That's mainly preference though, feel free to ignore it. Since you are stalling, however, Permafrost and SoG's is an amazing combo.
Retroviruses take up a lot of space for their limited use, so I'm not convinced about those.