Is the B-ray shoulder weapon worth using? It's weighs a fair bit, and only has one use, it also has a very long range on it. But it doesn't do any damage itself, only reducing the resistance to explosive damage on the target. If I use it to send a mech's resistance into negative numbers, ie, they didn't have any resistance to begin with, will my one missile launcher do more damage beyond what it would do normally, against a mech that was at neutral resistance?

The B-Ray reduces the explosive resistance by 8 or 9 depending on which version you use. This allows your weapons that deal explosive damage to do more damage. For example, if they had no resistance to anything, using it would make their explosive resistance -8. This lets your explosive damage do +8 more damage to the other mech. If the other mech had 14 resistance, then it would go down to 6. In the end, I guess it is only worth it if the battle lasts longer because that extra damage actually does something. However, if you have a really strong top weapon that does explosive damage that is let's say 80, then it would take more than 10 turns for the B-Ray to be worth it. That is 10 turns of attacking with damage. You can also use an explosive damage drone. That makes the B-Ray more worth it because there is more explosive damage. It really depends on your weapons in the end.

Depends on your mech type. If you find that battles usually last more than 8 turns, a resistance drainer is definitely worth using.

Here's an example that I commonly use to explain the effectiveness of drainers to my friends.

A battle starts you and your opponent. Your first two action points are spent activating an explosive drone and an energy shield. Your next action point you find yourself at range 3, so you fire a resistance drainer (doing -9 explosive resistance) and then a heat disolver (great static damage, mid-range heat weapon).

How much "damage" do you think your resistance drainer has done on this turn? Well, the display didn't show any, so you must've done none, right? Wrong! Your drainer has actually done 18 explosive damage. 9 extra damage for your heat disolver, and 9 extra damage from your explosive typed drone.

And this is only on the 4th turn of the match (opponent, you, opponent, you)! Every time an explosive damage dealing weapon or special (drones, hooks), your resistance drainer technically does another 9 damage. 6th turn, it could add up to 45. 8th turn? 72. 10th turn? 99. This is assuming you get off 2 hits from explosive weapons and another hit from your drone.

Each time you hit with an explosive typed item, even if your opponents resistance is still positive, your drainer still helped your explosive items deal an extra 9 damage each. Since the opponents resistance is 9 lower then it would've been. This also isn't negated by a resistance kit, since the drainer still made their resistance 9 lower then it would've been.

Hope this helped