What do you guys think of this power? One of my players took it a while back, so far he's only used it to jam guns and stop power weapons working, fair enough right?. However, doesn't it basically mean I can never field vehicles against the kill team, since one WP test effectively destroys them immediately regardless of everything? It has all that DM discretion stuff in the rules, but I'd really hate to just have to DM fiat the power to not work, especially since it's so specialised.

Has anyone else encountered this? When I first read the rules I googled it expecting a load of threads about this but there is nothing. It just seems really strong to me, especially considering how early it's available.

I believe you may have missed a bit. Machine curse works against (as the wording says) a single vehicle or lots of smaller devices and even then it's only disabled for the length of their PR, unable to move or shoot. It does not destroy it as you asked. So the vehicle does become mobile again. Plus it can only be used on ONE tank at a time, not lots. So you can still have the other vehicles unleashing hell. I would debate the practicality of this power on larger things as well, so the ability to disable a predator is probably fine but I wouldn't say they would be able to knock out something bigger or better defended like a Land Raider, aircraft or things like a titan as they are too large to simply jinx or have multiple redundancies in their systems to be overcome by a bit of sorcery.

However it does say that warded vehicles and devices can be resistant or immune to this power at GM discretion so you could say that the enemy Chaos Predator is protected by chaos runes which nullify their abilities. The best defence though is just staying out of its range, A las cannon is a good few hundred metres of range, easily able to shoot the hell out of them from ages before he can get near enough.

From experience, I feel like the power is vague enough on what it affects that it is ripe for abuse, or if not abuse, it's too broadly applicable compared to some other powers. It shuts down Tau and CSM solos way too easily, for one thing.

I know it doesn't actually destroy the vehicle, only disable it, but as far as I am concerned the ability to disable one for 6 rounds (if pushing) is the same as destroying it. Also, how many vehicles do you think I'm throwing against the kill team? I figured one predator supported by a few chaos space marines was supposed to be a challenge, but the predator might as well not be there. I could just throw in another predator on the assumption one will be immediately taken out of the fight, but that just seems like cheating since all I'm doing is compensating for the presence of the machine curse power.

As Kshatriya commented though, the power is vague enough to either work on a single vehicle and stop it for a number of rounds or disrupt the armour or weapons of a group of chaos marines for a single round. If they choose to disable the tank then it still doesn't affect the dozen or so marines from shooting them in the face.

While I did try above to defend the rule or explain ways of mitigating/lessening the damage as the GM you could choose to house rule the power or try to rebalance it. I do agree it is way too vague that you can knock out a Tau battlesuit because somehow it happens to comply with Imperial magi-tech nonsense, which frankly disgusts me. I didn't like Weapon Jinx as it allows the same. One thing I liked is that Black Crusade made psychic tests Willpower based with modifiers. To balance the power, what you may want to consider is something similar to the below:

Consider then the following quickly written possible house rule to allow you to readdress this:

The size of the item affects the potency of this power, with larger things being harder to manipulate than smaller objects with the possibility of more complex or more reinforced systems.

Apply the following modifier to the initial manifest roll (after determining psychic strength) based on the size of the largest item being affected if there are multiple. If the test is passed then all items are affected.

Size 1 = +10

Size 2 = +0

Size 3 = -10

Size 4 = -20

Size 5 = -30

Size 6 = -40

Size 7 = -50

Size 8 = -60

Size 9+ = Impossible, cannot be affected.

I know it doesn't actually destroy the vehicle, only disable it, but as far as I am concerned the ability to disable one for 6 rounds (if pushing) is the same as destroying it. Also, how many vehicles do you think I'm throwing against the kill team? I figured one predator supported by a few chaos space marines was supposed to be a challenge, but the predator might as well not be there. I could just throw in another predator on the assumption one will be immediately taken out of the fight, but that just seems like cheating since all I'm doing is compensating for the presence of the machine curse power.

I am typically very uncomfortable with the "pull out a MacGuffin to prevent use of the player's MacGuffin" style of GMing but in this case I'd say it's perfectly reasonable for Chaos to ward their tanks against psychic powers.

Now, Tau doing that would be unlikely since they have a very weak warp connection, but my long-term plan in a game was for some high-ranking Tau to be wearing a crystal lattice mantle of Nicassar design, which would basically negate incoming psychic powers against the wearer. Punctuated by a Battlesuit commander saying "Problem, Astarte?" over the mic before tossing out some railgun shots.

For Tau you arguably don't need a warp connection to negate it. Why should something which is designed or can be arranged to knock out Imperial technology by jinxing it effectively deny a completely alien system from working? The power says that it calls down a curse, probably to disrupt the Imperial machine spirits. However Tau stuff wont have machine spirits (or none that the mechanicus can discover) so why would it be affected by something which disrupts one? Wont affect an Ork vehicle, some of them dont even have engines at times and only work because they think it will.

Worst case scenario, give it a shield generator. Forcefields block psychic powers

I'm very much with Kshatrya on this one. If my players can reasonably shut down my baddies, I don't nerf them for playing intelligently. So they cake walk across some of my encounters. I'm the GM. I get to define their missions and draw up their opponents. I'll still throw the occasional bone to the Librarian so he can impress his friends with his "kewl powerz," but most of the time they won't be facing a predator again at close range.

Really, most of the psychic powers I've heard people complain about on forums are easily taken care of at a distance. In fact, almost everything I've ever heard people complain about being over-powered becomes a non sequitor at 300m (except the heavy bolter).

Also, how many vehicles do you think I'm throwing against the kill team? I figured one predator supported by a few chaos space marines was supposed to be a challenge, but the predator might as well not be there. I could just throw in another predator on the assumption one will be immediately taken out of the fight, but that just seems like cheating since all I'm doing is compensating for the presence of the machine curse power.

This is your problem, GM. Take out the latest Codex Chaos Space Marine (or any other) and create a 800 point army list. Confront your players with it in DW and let them figure out how to pick it off one by one. Problem solved, next!

Alex

In Black Crusade they have lots of vehicles the are demonically possessed. That would make a for a nice twist where your KT's ambush falls apart as machine curse wouldn't work on it.

But otherwise, just scale up the encounters. So the predator will be out for a few rounds, that means the psyker is disengaged from the fight with tying up the predator instead of smiting all the chaos marines before they can get into h2h range.

Or even better, have a sniper have it out for the psyker so he's choosing between gimping the vehicle and taking accurate shots or taking cover to avoid dying.