Let's just think about the title for a second. "The Deceiver".
What can be Deceived? Senses.
What senses are there? Sight, hearing, smell, taste, touch. (I'll stay with the common 5 and more or less exclude stuff like sense of direction, temperature or time)
Which of these 5 could be influenced by a video game mechanic? Mainly sight and hearing to some degree.
Smell, taste and touch? Nope.
So right of the start the concept of "The Deceiver" is ripped of 60% of all the possible things to deceive. Well then, what about that which is left?
Sight: Here we could go with seeing double/clones (seeing things which aren't there), not seeing things that ARE there (aka invisibility), twisted controlls (sense of direction). The first 2 things are actually included in her kit. LB's passive includes double vision and invisibility and her E makes you lose track of her.
Twisted controlls, while actually being part of multiple video games in form of reversing left-right, up-down, back-forth, this would be impossible to execute fairly in a game with strategy like top down controlls. Deceiving your hearing ability is also not possible to execute fairly in this sort of game.
BUT to be fair right now I'm talking about Deceiving the player and not the champion. There are still more two things within this games mechanics that are fitting for a "Deceiver". Impairing vision and fearing the enemy and I think these mechanics could be included in her kit with enough effort and changing her into a control mage.
"Deceiving" shouldn't mean making you think you have an HP bar. And yes, I know that is what her one and only joke is all about, but who cares? Ezreal lost his in his update as well so screw her bad joke.