Warhammer 40,000 seems like an incredibly difficult universe to balance, because depending on which Codex you're reading, every faction seems like the toughest, meanest, coolest guys out there. The Tyranids have the numbers to eat the galaxy ten times over, the Drukhari can literally steal suns, and the Necrons just get back up after taking a mortal wound.
For the single-player campaign of Warhammer 40,000: Dawn of War IV, senior game designer at King Art Games Elliott Verbiest explained that balance wasn't always at the top of their priorities list when it came to making sure factions felt like they do in the lore and tabletop. Necrons, for example, get the use of a resurrection orb to bring their units back.
"When you are playing in singleplayer for example resurrection orb feels amazing," Verbiest said (via PC Gamer). "Your units have been defeated, here's something that brings them all back. Doesn't sound super great in a multiplayer setting."
For multiplayer, then, the mechanic was changed, allowing players to bring units back, but at a much slower pace. "We've conveyed it now in a way that also offers other players a form of counterplay," Verbiest said. "You can destroy the structures, it takes time for the necron units to come back, so there is a window in which you can do things in that meantime. Those are the kind of things we've considered in order to still bring across that core fantasy, and especially for the campaigns we go all out for that kind of stuff."
It seems players are really taking to the game, as Verbiest also said a main point of feedback is slowing the combat down, as the feel of it is so good that players don't want a battle to be over.