@Damping Matrix.
I thought a lot about adding Matrix EVEN agaisnt Dragon, but I usually use the same strategy Zherbus is using.
I add only StP, BeB, Crypts, Disenchants keeping, Stiffles, and all the other maindeck hate for a simple reason. Usually Dragon pack In a lot o Deed and Verdant against Keeper. So Matrix would be REALLY effective only if I maindecked it for a Metagame Reason. After siding, only the Combo Part of the Dragon Strategy would be touched by D.M., while all the other Reanimating One is totally free of be used in a vey effective way. So, talking about Space, I dind't found useful to add ALL the other hate cards AND D.M. . To side all this things I'm sure that I have to diluite too much the power of Keeper post side.
This is one of the few matchup during which I wish I had up to 8 StP

Against Tog, I fear that D.M. should be used because of "Tempo".
Atog is really effective if, while you are
running to fight is better draw engine and his better winner and his better defences, he can submerge you in few turns.
D.M., as CotV some weeks before, let you have the Tempo needed to steal Crucial Turns to this solid opponent. If Atog would act in his near unstoppable ComboMode, so few things could be done to slow him down. In all the other situations, D.M. is the only way to slow the game and let you breath before the possible win.
What do you think?