agree with all your points, having the narrow view of "only this set of mechanics may be covered by items" can reduce creativity. however there is precedent for most items currently in the game existing in dota in some form. Something about the semi permanent nature of mines makes me feel it...
I think it sounds pretty fun! However, the tooltip is very complicated and I think that's a worrying sign when an item is confusing. Also when I think of items, I think of more general, all encompassing game concepts like "silence enemy" or "give someone a shield". Dropping mines sounds like a...
I don't disagree with you but this is a place for feedback and everyone is welcome to post their ideas. (just saying maybe those first sentences aren't necessary xd)
I don't love the idea of Liandrys being in the game considering there are already multiple %hp solutions like Bleed, Decay...
Regarding the "courier" that follows her, seems like good opportunity for a vector targeted ability. Not sure what the dev's plans are regarding them, but there's potential there.
LOL the fly cam is completely unnecessary but very appreciated. I like the idea, iirc everyone had a hoverboard(?) of some sort that they drove around on either in a super early build of the game.
the way abilities modify based on level is already like aghanims imo. maybe there could be a set of "aghanim items" that fulfill various arcehtypes in the game. making them objective based/pve sounds good interesting