Cho'Gath Jungle Tank:
Runes: Grasp of the Undying, Conditioning, Overgrowth, Trancendance, Gathering Storm, 1-10% CDR, +6 armor, +6 armor
Items: Chilling Smite Cinderhulk, Warmog's Armor, Spirit Visage, Ninja Tabi, Frozen Mallet, Sterak's Gage
Logic: You have good dragon and rift herald control early with double smite and ultimate at level 6. I regularly get 11-16 stacks per game, and have anywhere between 7k and 9.5k hp on most of my decent games. At end game, you can delete a squishy in a teamfight and get even more stacks with R, and end-game sterak's gage is silly big. With this build, your autos and E's do most of your damage, and so does your ultimate. Since it's a 0 AP build, you only use Q and W for jungle clear or for utility in a fight. The E is your main source of non-ultimate damage.
Kassadin Hypercarry Mid or Top:
Runes: Electrocute, Taste of Blood, Ghost Poro, Ravenous Hunter, Manaflow Band, Gathering Storm, 1-10% CDR, +9 adaptive force, +6 armor
Items: Hextech Gunblade, Nashor's Tooth, Lich Bane, Rabadon's Deathcap, Void Staff, Sorcerer's Shoes
Logic: You already have a mini nashor's and mini lich bane in your W, so building both is great. Hextech Gunblade adds another spell almost with it's active. There are decent penetrations, high AP, Max CDR, mana regen, and, if you get ahead enough, 1-hit KO's. However, remember that laning can be difficult. An example of a fed Kassadin with this build is this, when I was ahead and got back to back to back 1-hit KO's in this clip:
https://www.youtube.com/watch?v=Kfbjt6WkROQ
Udyr Hail of Blades JG, High AD.
Runes: Hail of Blades, Taste of Blood, Ghost Poro, Relentless Hunter, Legend: Alacrity, Triumph, 10% attack speed, +9 adaptive force, +6 armor
Items: Chilling Smite Warrior, Ravenous Hydra, Berserker's Greaves, Death's Dance, Essence Reaver, Infinity Edge
Logic: Your Q does 175% Bonus AD on the first and every 3rd strike thereafter. Q also grants big attack speed (which gets diminishing returns the more of it that you get). Therefore, exploit it and build high AD items. I think I've gotten over 600 AD with this build before, when you have a couple of infernals, which grants a massive 1st and 4th strike when you use Q. Warrior enchant grants a massive +60 AD for just 2600 gold, and tiamat grants +25 more AD and big wave clear for 1325 more gold. You get big returns for spending that gold, as hail of blades with Q up grants you a big burst of damage on your first Q rotation. Berserker's Greaves' 35% attack speed is the most efficient and only attack speed buy you'll need. At end game, a Q rotation will grant 1300 bonus damage per proc, and your regular attacks are critting half the time also. Relentless hunter and Bear Stance spam helps you to roam very well also if you need to split push. Using your Q mostly in fights after mid game has you topping the damage charts and deleting people one by one. You may be vulnerable to mage artillery with heavy CC, or tank teams with heavy CC, but if they load up with damage dealing squishies, you can pick them off well.
I'm sorry I only have footage for Kassadin uploaded at the moment.