Though these might not make it into the real game I really like the spirit of them. Little goofy effects that change how you approach a character seem like an interesting step for the game.
There is an unfortunate animator's hurdle to implementing an item like the jar. For example, Abrams' slide has his back grinding along the grounded surface and that just rubs me the wrong way for some reason.
Besides that point, the effect might be too minor? In a weird way, I feel like an item like this does offer some decent damage reduction but it needs some way to not just be a roundabout bullet resist item.
SO HEAR ME OUT Jar-in-a-Head can be retooled as the cursed upgrade Headless Frenzy as a thematic upgrade to the eponymous item. (and would be a good bouncing off point for additional bonus effects to go along with!)
I think if Viscous' head were to change color in response to having been lopped off it might be okay. [Who knows, the redesign might tackle this problem in its entirety anyway, if he keeps the baseball cap from his old redesign, for example]
I really like the goofyness of the big head mode, it kinda reminds me of something I'd see in a random older source game as a weird offshoot commmunity gamemode. (though cause of that, its probably an ill-fit for regular play, probably better off in Street Brawl or when more Arcade-like modes inevitably come out for this game's full-release and after) [Also something about FoV as another possible hurdle to implementing it, keeping the head from blocking yo damn screen]
I like the idea of more knockback resistance items, considering displacement is kind of a state that happens A LOT and not just reactive barrier...
Being marked on the map constantly brings an interesting idea into play but not really sure if it's a reasonable enough downside, higher skill players usually don't have a problem essentially deducing a person's location even if they aren't explicitly visible on the mini-map. (Though it's obviously really bad for any heavy gankers like Calico or MnK)
Baba Yaga is such a cool character from folklore and seeing her throughout popular media is always a treat, a perfect fit for the occultic secret shop of Deadlock. [Though the idea of the infamous Rat King being cast as the shopkeeper works really great as well and a nice nod/inside joke for the community...]
Anyways I decided to write a whole lot for no reason in particular but I hope you appreciate it.