Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
With flat hybrid masteries and whatever playstyle or champ you pick, some penetration runes as well as lifesteal/spellvamp and xp for early game gold wrecking (the build is costly!), you are virtually set. The basic attacks mean no skill required! The spellblade is especially good for champs with passive abilities or auto-att-scaling abilities like jax w, eve q, udyr in general (q mainly but r for damage, w for instaheal and e for dat stun), tris/mf grievous wounds att, ez after w or landing his skillshots, tf w, kayle e, teemo after q or shroom or even his w, nasus q, etc.
The champs I listed above are my troll hybrids for the first five, and then in order of usefulness (degrading) the next five. Anyone you think is good hybrid, go ahead and try the builds.
Always rush sword of occult and mejai's soulstealer for the scaling AP and AD per kills/assists early game; it will help you wreck and farm.
If they build defensive for you, get the last whisperer and void staff for the troll penetrations. They're rendered powerless after your penetrations.
Trinity Force is good for a little att spd, some mvmt spd while autoing, and of course the spellblade. Lich bane is a good alternative for all of the above minus att spd, but plus mana and ap.
Honestly, for defense, there is not much to buy; however zephyr is good for the anti-CC and of course guardian's angel for the bonus mr/armor (and the respawn). Boots of Swiftness is what I prefer, with distortion if you do flash/teleport. If you dont have either of those (or ghost) dont get distortion as it is less cost-effective. If you're more of a teamfighter, go for captain; if you're losing, get homeguard; otherwise alacrity is best. Furor is only good when you're hitting things eternally, so if you trust you will be hitting things all the time (from a range like tf or kayle), then get furor; otherwise I don't recommend it. Wit's end is also good for a tiny bit of mr.
Of course, hextech gunblade is best for the spell vamp and life steal. If you're still not doing well after that, then get guinsoo's rageblade for bonus. Ravenous Hydra is always good for the AOE (or runaans if you're ranged).
For anti-tank purposes where they are mundo-like or zac-like or naut-like with tons of health and literally no armor or magic resist, you want the max health bonus damage items. Blade of the Ruined King and Liandry's Torment do the trick for you, depending if you have an actual ability that deals damage or you rely on your auto-attack more. Both is always troll, though kind of useless depending on the champ. (Teemo for example is perfect to have both.)
Careful with these builds; they are meant for 1v1 and render you almost useless in teamfights or when ganged up on, so don't get baited and play careful. Losing stacks on your mejai or occult make you lose power. I would jungle or split push, simple as that.
Also, jungling is perfect for this. Besides whatever jungle item is ideal for your champ, wriggle's is always a good alternative if it works as once it transforms into feral flare you get MORE bonus damage (like nashor's tooth) AND some heal to go with it. If you're nasus and a game seriously goes that long, your feral flare farm will make you seriously wreck with your q. It's totally unfair.
Want some bonus cc? Specifically slow? Then Rylai's and Frozen Mallet is PERFECT. So much slow, so much troll, so much win, and the bonus health and ap/ad is perfect. You'll love trolling with that; eventually you're going to want to lose those items, though, but in good time.
And there you have it. Adjust your build accordingly to your situations, but stick as close to core building as you want if you want to troll and kill things in seconds, and one shot all farm and jungle (including the solo baron). Have fun!