are you allowed to use more than one at a time or do you have to wait to use a second one?

I would assume this is the same as any other ship buff. Only one at a time. I believe it only lasts for a minute or 2, but by then you've either conquered and don't need another or failed and have to wait 24 hours anyway.

Now if you are thinking of the bio-vaporizers... yes you can use more than one. First hand experience on that.

no it was the mutagenic cartridges, they give 1500 attack for invasions, I was just wondering if it was stackable. there's a planet I've been trying to conquer but the guys has more defense on it than I can power over I was hoping they were stackable so it would make it much easier on me.

Remember that they only affect invasions, so it won't help with killing the population.

I know, the guy has with a legion bonus, and guarding it, 3,748 defense, my attack isn't quite half that unboosted. I know I could knock the guy out no problem considering his attack and defense are both less than 500. it's the planet itself. what I think happened was the original owner got it stolen by someone else, then this guy somehow managed to snatch it away from the other player without it being stolen back. I would know if it was fluxed. I've been trying to steal this damned planet since I started playing but was too weak when I first started and he's only put better equipment on it since the update. so now it's in this weaker guy's hands. and I'm waiting for the perfect chance to try and finally steal the damned thing. haahaha.

My advice would be this... Don't go alone, gun-up your ships as good as you can (8 of your best tech if at all possible), buff your attack/defense with obelisks and such, wormhole everbody guarding the planet, throw a mass-disruptor and an ion storm at it, drop a bio-vape or 2, use the mute cart, and invade. And have a flux ready because you WILL get attacked back.

Me and a legion mate used this exact technique to recapture one of his planets that was essentially turned into a brick. Took all of about 30 seconds. Would've been faster but he failed his invasion roll and had to tell me in the chat so I could take a shot at it. That wasted about 6 seconds till I could click my mute cart too. All this while the guy was online too.

Shock and awe. We actually got complimented about 5 minutes later by the guy.

I don't think I have a mass disruptor. is that mission item or an npc drop?

Orbital Mass-disruptors are available from a Lazuli Harrower. Matched Uncommon NPC. The lowest confirmed sighting is Rank 88.

I don't think I've seen one of those.

be ready with artifact fot that too those harrowers can be wicked strong.

I haven't seen any of those and I'm over 190 now.

I'm 255 an i've seen two of them. They first appeared on my battle tab about three weeks ago, and the first I'd heard of them was about a week before that, so I don't believe they've been around long.

If you want one, just keep fighting NPCs. Lots and lots and LOTS of them. Some people don't seem to get this, but the more NPCs you kill, the higher your chances are of finding a specific NPC simply because you see more of them. Think of it like the lottery. The more tickets you have, the higher your chances of winning. Same goes with NPCs, except that instead of having lottery tickets, you have to KILL NPCs. Killing them is all that matters, not simply damaging them, so make sure you kill them as quickly as you can for as little energy as you can - so equip arties and go on an NPC kill spree.

They are matched rank that meaning that you can see them, basically, at rank 1. On the other hand although I got 9 or 10 of those this far the NPC hunting it's, like almost everything in this game, random. Meaning that you can kill more than 100 NPC's in a hunt without getting anything noticeable.