Lets start with true basics.. What is your diet like? Make sure you have your diet down, then look into a few of these (if you have not). For wanting to gain 10ish lbs, I'd hop on 4-5k cals (depending on your maintenance cals, metabolism, etc). Check out MyFitnessPal (if you have not already), great way to track calories and make sure you're hitting your macros. Now basic supplementation:
-Creatine: 3-5g per day (timing is irrelevant ). And once you've hit saturation, no need to dose on off days
-Beta Alanine: 3.2-5g/day. Dose on off days
-Betaine Anhydrous (TMG): 2.5-3g/day taken preworkout. Dose on off days
-Citrulline Malate: 6-9g/day, taken pre-wo
-Agmatine: 1-2g/day taken preworkout. Can also be taken with meals for GDA effects
-GMS: 3-6g/preworkout. Can be taken daily. Will help with pumps and fullness.
Other supplements to consider:
-Pre-workouts: There's a vast amount of great pre-workouts around (Mr. Hyde, Hemavol, C4, PSU, Myo-Blitz, etc) take a look and choose what you like best
-Forskolin: 50-100mg/day taken throughout the day, best with meals. (For you purposes though this may or may not be out of consideration)
-Anabeta Elite: 4 caps/day taken pre-workout. Increase in fullness, strength, etc
-Phosphatidic Acid: 750mg/day taken preworkout. Increase in fullness, strength, etc.
-ArA: 1000-2000mg on workout days taken preworkout. Increase in fullness, strength, etc. (Invalid Link Removed good read here
Also a lot of new "natural anabolics" on the horizon to take into consideration. SARMs (ostarine, s4, lgd, mk 677) may be something down your line. My suggestion for a "natty stack" would be an ArA stack.
ArA help:
The standard ArA cycle would contain;
1-2g ArA (1.5g seems to be the sweet spot)
2g LCLT (or some form of carinitine)
3-6g GMS
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Advanced Cycle:
1-2g ArA
2g LCLT
3-6g GMS
2-5g HCA
4caps ABE/Compound 20
Each having their own reason, of course.
Carnitine would would inhibit ArA being broken down into thromboxanes, enhances lipid packaging and enterocyte (lymphatic) absorption
GMS enhance emulsification in attempt to kinetically enhance the delivery of ArA to the enterocytes, and then to the lymphatics
HCA will aid in cellular uptake of extra ArA
Anabeta Elite/Compound 20 (via the ingredient Lodhra Bark) going to inhibit ArA being broken down into luekotrienes
*Must note while all these will produce results (with a good diet) they still won't hold up against PH/AAS. GL