I really really used to love this card. Part of that is that it was my very first Epic, so there's some nostalgia. But it also won me more than its fair share of games. But since the change with version 0.98, it just seems completely worthless.
I will grant that the old version was rather buggy. It took a loooong time to resolve and occasionally crashed the game. The 4/4 0 morale zombies were recreated every turn if they died (and possibly new ones were created if other creatures died, I never took the time to count exactly). Then, from a gameplay standpoint, moving around the dozens of zombies you got was something of a chore and made the last turn or two drag on with extensions.
Before, it struck me as a powerful yet very balanced card (if the immortal bug/exploit was removed). Sleepers are not good at accelerating their gameplay, lacking the Warpath's tools or ways to reliably protect Nobles. Thus, devoting several turns in the late game boosting base resources instead of playing or drawing cards is a very risky play. It was always a sort of Hail Mary, all or nothing move to take when the deck's main strategy was countered and foundering. Even when it paid off, Yuanshi's Wrath, Mass Death, Winds of War, a double Heat Wave, or a lingering Mega Unit 02 are all commonly used cards that can hard counter the play. Now that Sacullas is double purity, you wouldn't even be able to cheese out a win with him. High cost, high risk, high reward: in other words, a well designed Epic rarity card.
Now? Well, it's still 14 cost, so remains very difficult for the Sleepers to play. It's going to be late game by definition, with no ways to cheat it out early like you can with so many high cost characters. So now, instead of getting a huge tempo swing for your investment, you get control over a random handful of leftover characters, don't clear what is a likely losing board position, AND open yourself up to a probable morale loss because all those lovely characters you now control all hurt your zombie overlords' feelings when they die.
So, a side by side comparison to a similar card: Avarrach Has Risen
Cost 14 (investment of 50: 9*4 to raise, +14 to play) vs. Cost 12 (investment of 30)
Gives opponent's leftover cards in deck vs. gives all cards that have ever died on both sides
So my verdict: the Virus a card that didn't need a nerf in the first place, yet has been nerfed completely out of playability. And I wrote a surprisingly large amount about a single card change.