Shyvana's Twin bugs
Currently, Shyvana has two bugs, neither of which are gamebreaking, but a mild inconvenience.
The first one is: When in Dragon Form, using Twin Bite on a Tower or Ward will only proc the damage from the first autoattack (i.e only does 1 damage to wards, and only hits turrets twice.)
The second: When using teleport on a tower, if Shyvana indicates she wants to cast a max range Dragon's Descent the frame she finishes teleporting (not sure how soon after appearing exactly, but it's a very short window,) she will instead dash in the opposite direction.
Both of these can be reproduced with a 100% success rate (although the second one requires some practice.) I know that Riot are hesitant to change Shyvana until her eventual VGU, and these are fairly low-impact bugs, but the second one I discovered by accident in a ranked game.