They will infect units for 1-2 turns :) (and then, after death, turn them into zombies:D)
Added 6 minutes later
And also, they should be able to jump to neighboring living units. To avoid this, even complete immunity to magic is not enough; you need the "clean freak" ability :)
Демократия есть одурачивание народа при помощи народа ради блага народа.(Уайльд Оскар)