have Du ever watch an Anime that was really good but left Du with a cliff hanger and Du couldn't get the Bücher to see how it ends

Nope! nothing like that

Mahou sensou ( wells its my guilty pleasure but!!)! Someone got hurt, people were fighting, and there was a time jump all in the last episode! What happened next? Well I sure don't know since the Quelle material it was adapted from isn't available for me to read (well it might be online but I don't like Lesen online) also low key rokka no yuusha since I thought all's well that ends well until they threw in that twist

unfortunately yes:
-re:zero
:pandora hearts

:/ decieving (crying internaly)

Gangsta. left me feeling this way. Luckily I found out that there is a Manga so in the future I do intend to read it.