Predecessor Builds > Gadget > The electric oven
In the current meta with so many frontliners and bruisers, especially those with self healing (looking at you, khai and grey) and with the huge buff to caustica, and reverts for megacosm and tainted sceptre, I've been finding this build to be extremely effective, cooking all the nerds out there.
For skill level order I'll take rmb 1st, then q, then e, then focus q>rmb>e, and look to poke out my lane opponent. Of course this is not always suitable, and in those situations I'll focus rmb over q and just focus on farming.
As for buy order, I'll rush cosm, get the stick for tainted, then caustica, and depending on state of the game and who the enemy comp is made up of, I'll either finish tainted or go straight for wraith leggings. Game is usually other by this time, but if it's still ongoing I'll go the other (so wraith, or finish tainted) and then go for oblivion crown last.
This build absolutely cooks everything, with the insane mag pen of caustica, combo'd with cosm and tainted, you'll be serving up tasty meals in no time!
The situational items all come down to match up and team comps, and would replace tainted if they don't have any healing (which is highly unlikely) Now, I know what you're thinking "Azure, situational, wtf is this guy smoking?!" The thing is, Azure just isn't that good a take right now imo, it used to be great to pick up alch rod, rush cosm, etc, but in the current state of the game I'm finding going alch rod 1st heavily delays the actual power spikes Gadget wants and makes you come online a lot later than needed with current game pacing. Now, in higher level/comp play, alch rod>orb> cosm is likely a very solid build path, but in solo queue plat and below, I don't see that doing well at all as while you're building stacks, the enemy laner is farming your duo lane.