Yes, Slazer does base it’s % increase damage dealt on how high the heat level of Plasma Pulse. Thermal Equilibrium can be chosen if you have already gone for this helix mutation as it only applies when Failsafe is active.
Now wait just a minute there sir. What are these words I’m seeing used in the same sentence, Reyna is garbage. Hmm I’m gonna have to stop you right there cause you are doing all sorts of wrong things.
If you are trying to do any sort of damage with her you need to just stop and play Marquis cause you are a SUPPORT, yes that’s right a SUPPORT. You help your team by shielding them and making them do more damage, just throw away the whole idea of you doing damage. “Oh but her over shield is on a 20 second cooldown.” It’s a magical thing called CDR, oh wait I need to spell it out for you Cool Down Reduction. I consistently get that overshield to have a 8 to 10 second cooldown. The only damage you should ever go for is when the game forces you to get damage. If your overshield is breaking from enemies you need to stand back and let other people who actually do damage stand in front of you. The only time you should stand anywhere closr to them is to throw an ult around a squishy getting focused down.
Gear? Build? Please?? I’ve been trying to build her for cooldown and even with 10-12% cooldown across my gear, I could only ever knock that 14 secs down to 13 secs 
I don’t have the build on me since I’m not at home at the moment but the only solid thing I have is the legendary that reduces build cost and gives all turrets you build a 5 percent chance to crit other then that any rogue cdr item is great on her since you should constantly be spewing out abilities but the main thing I would say is at level 5 get the 15 percent cdr as long as you have an overshield on yourself. Once you get that stay back in the fight and be a complete coward and buddy up with someone.
Cute how most people completely underrate reyna, same people are trying to nuke her in a match and end up fleeing with less than 10% life… yes reyna is a support hero, but the difference is, unlike miko and ambra she doesn’t need to chose between healspec and dmgspec, she can do both very well, from lvl 2 on i can beat 75% of my 1on1’s , from 2 to 8 you can easily get some kills, from lvl 8 on she is a ■■■■■■■ killer, if you know how to play her she’s by far one of the most dangerous and effective hero on the field, supporting allys with overshields and her prio dmg debuff, on the other hand she heals with overshield, granting +120 shields from lvl 1, which basically means you can completely bypass any shield recharge delay from lvl 2 your homing pulse cannon is unbelievably helpful asset to support your teammates while they are nuking other heros, from lvl 3 on you’ll start to hurt people with a +50% damage boost for your lasergun, lvl 4 either more healing per overshield or, my suggest, take the +16% damage buff mutation, your pulse cannon as well as your lasergun deal even more damage, lvl 5 ulti unlock and the -15% cooldown when you launch it, lvl 6 more overshield strength, keeps the +16% dmg buff longer live, lvl 7 +18% pulse cannon damage, lvl 8 double the prio dmg boost from 16 to 32%, lvl 9 overshield duration from 8 to 14 seconds, lvl 10 take the mutation where everyone in the bubble gets an overshield, so, when i’m playing with my thorne mate, he gets an overshield, we both get +16% dmg, prio adds +32%, blast your homing pulse until it overheats and you can add additional 50% for your lasergun, i carry a Vow of Vengeance (+10% dmg, +7% attack speed), a cooldown clock (around 15% CDR if i get slowed or CC’ed in general) the third item depends on my team, with another healer i take an +10% attack speed item, otherwise an + 15% healpower item, yesterday me and thorn played an incursion match where i got out with 17 kills, 1 death, 22 assists and nearly 90k healing given, my thorne mate had 13:1, we managed to hold the line against 3 other players and their minions for like 7 minutes, no way any miko can manage that, i know it cuz i mastered miko aswell, he’s good, but a well playes reyna is worth 3 mikos, so my condolences to you and everyone who haven’t the oppurtunity to see a real reyna in action, maybe we meet sometime on the battlefield, them you’ll see how “useless” and “garbage” she is 