Famine and Death are the the "best" ones, both on invades and defense. Plague is fun on invades. War is niche, but not altogether super useful. Drakk is a tankier Crimson Bat with more mana colors and thus can do pretty much the same stuff Bat can do. You'll probably be having two at a time available while catching up, so War/Famine, Plague/Death, Drakk/(next one). Tough choice there, since Famine can absolutely stop a team in its tracks and is, in my opinion, a cut above every other one in terms of raw power, but if I had to choose, I'd probably go for the Plague/Death week. Death is one of the two I'm missing, and I'd actually use him, unlike War.