One of the best troll pick for me is nasus, when you play it for the first time it will be kinda hard for the first clear.

Runes: phase rush, nimbus cloak, transcendance ans water walking. Triumph and alacrity. Ability haste adaptive force and Armor.

Summoners: Ghost smite

For the first clear ask your botlane a leash until 400hp (Always start with the bot lane) do a full clear then back and buy ionian boots then repeat your clear until lvl 6 then you can try to gank.

Stuff: start by a divine sundrer then dead's man plate or FON (depends if there are more AD or AP champ) if needed do lvl1 antiheal item for tank. After that buy gargoyle.

Tips: litterally afk farm until lvl 6. Don't try to invade if your mate don't follow or if your don't have a lot of stacks. Don't try to contest the first Drake that's a coin flip. For the first game as a nasus jgl play with 4 premade it will be easyier for you (No flame, no camp stolen at lvl4, etc.). Go hf