I would say ALWAYS test your build on a regulated device, or at the very least an Ohmmeter meant for vaping, and visually inspect for any possible shorts, and remove them.
A nemesis is a great mech which I own 2 of, easy to use, and only a tenner and under from fasttech.
I use Samsung 25R's, I have an american friend who runs a very large battery supplier, and checks all batteries before sale, their real amp rating ETC (The new EFEST 'in house' batteries I got appear to be LG HG2 rewraps for example, with a 20, not 35A constant rating).
He advised me pushing a 25R a few watts over wont even result in damage due to samsungs liberal rating of their batteries. They probably could of safely rated it at 25 amps. (Plus the 40 A pulse rating for 5 seconds, and 30A for 6 seconds is good, but we should not rely on pulse ratings alone.
The lowest safe build is around 0.23 on a 25R, and that pulls about dead on 20 amps, but 0.2 pulls 21 Amps, so only one over, and because of the liberal rating you could do this, without even damaging the battery (The HG2 rewraps being sold as 35A are being used at 30A all over the place, they should not vent but will severely shorten their lifespan if used constantly at this Amp draw).
0.22-3 is still about 85 watts though at 4.2 V, dropping to 65 at 3.7V, around when you should pull the battery on a mech.
A multimeter might be handy if you are not sure you are pulling at the right time, I wasn't, got a multimeter, and found I was pulling them much too early, hence my short vaping time on a mech! Now I get 4+ hours, but I use a 0.5 coil which pulls 8.4Amps and is only about 35 watts, dropping to about 28 when the battery needs pulling.
Here is a great calculator that covers everything, coil wrapping, juice making, battery drain, and even more called steam engine. If you select a Samsung 25R from the menu, remember to change the C rating from 8.8 to 8, as the 20R was 22 amp, they made an error on the 25R and also put that as 22AMP, 8C is 20 amp on a 2500MAH battery, then you can enter your planned build and it will tell you what it will pull from the battery.
Battery drain | Steam Engine | free vaping calculators
(NOTE: 25R's are about the best all around battery due to their MAH, amp rating which is very liberal, and such, but try to stick to below 20 Amps if you can as you can still get plenty of power if you want clouds from a 0.22-3 build,88 watts is a lot of power. I don't often go over 80 on my higher power regulateds, and when I do, it is a VERY hot vapour. )
Just make sure to get a nice clone, setup it correctly (easily done, you adjust the firing pin height by screwing it in or out, and the top connection by screwing in or out by hand, untill you have connection with the mod fully closed, if you have them too close together the mod will not fully close, it will still work but wont looks as good as a well set up mech).