I've been learning what Deadlock's items actually do, thanks to this player-made build calculator that I can keep open in my tabs

pcgamer.com:

To a newcomer, Deadlock's builds and special items can be confusing, especially if you're more of an FPS player than a MOBA one. You can always practise making builds in-game, but it can be a little hard to think big-picture when you're trying to stop Adams from crushing your lane. Luckily, one player decided to create an easy way to do so. 

«I made a Deadlock build calculator,» alayton says. «It's actually more than just a build calculator, but that's the big headline feature right now. There's also a complete list of heroes, abilities, and items, with data from previous versions being preserved. The big plus here is that this data is being read directly from the client, so updates are fast, easy, and cover everything.» 

The website's name is Mutex, and it lets you pick any hero you like and start creating various item builds. Instead of having to go into Deadlock's sandbox to see how your item choices will impact it, you can just use Mutex to quickly add and subtract them. The weapon, vitality, and spirit stats will change as you mess around, so you'll learn quickly how different items affect your stats. 

«We've all used the sandbox for playing with builds, and this can't directly replace that,» alayton says. «There's no way to import builds into the game currently—but this does let you play around with builds when you can't (or just don't want to) run the game. 

»I approached builds a bit differently. Instead of being a step-by-step, buy this, then this, etc type of system, it's focused on seeing the effect of a specific set of items on your hero, whether that be your hour-long endgame goal or a more typical 25 to 30k soul target. It does still allow for adding early game and alternate items, but they aren't included in the stat calculations unless they're in the 12 main slots." 

You can create builds in the game's sandbox mode, and it'll give you plenty of information on stats and weapon status, but I found that playing around with Mutex is easier and quicker.