I have been spamming this hero prior to the 15min shard and it was decent but now with 15min shard once u get the shard at 15min with soul ring tranquil ur the strongest hero in dota at that timing. The hero is quite strong in lane with spamming rocket on their pos5 when ur about to pull and they literally cant stop u, once u get lvl3 u have so much damage its insane, one of the best thing about the hero is its scaling stats for a pos4 u get a lot of str gain and agi gain so u have a ton of armour and hp with no str or agi stats items so u are almost never squishy like a mirana is.
For the items i have tried basicly everything and nothing beats the soul ring tranquil combo it allows u to spam rockets on cd on whoever is laning and give u more hp which makes u evan tankier with higher armour and u never run out of mana than u start saving every gold to buy the shard at 15min because its too op if u put the rocket on the right target. for the next item i dont think any item beats getting dagon(the stats it gives u are also a +), the eblade change made it do lower damage now than dagon on gyro since it gives more int. Once u get 2-3 levels in dagon if u still have time i highly recommend refresher and do all the combo twice double ultimate, double rocket on 2 no bkb targets,double dagon than go in and clean everything with ur q, which basicly almost guarantees any team fight win. With these items u are almost always 1-3rd highest damage in the game if u play it correctly with std pos4 farm which is insane especially since its not damage over time like veno but more targeted burst team fight dmg
Source: https://www.reddit.com/r/DotA2/comments/u6d4nh/casual_reminder_to_pros_gyrocopter_pos_4_is/