I have some ideas for changing Scrolls of Teleport.
1) It needs a blindingly obvious cast animation. This is a general problem actually, I have a very hard time telling when enemy DGs are casting due to playing with details really low and the fact that you can't have a zoomed in, top-down view. Its especially annoying with teleports, because if they get the cast off they get away and you don't get the kill.
2) I would prefer that scrolls of teleport automatically target your citadel. The best use for these seems to be escaping from a fight while near death, in which case you probably want to get to the health crystal ASAP. Porting to the citadel gets you near the heath crystal, and it removes the need to zoom out and target the citadel or health crystal manually. My computer is pretty slow and zooming out drops my framerate. This is the primary item that requires zooming out to micro effectively. Also, when you're about to die, you want to be able to cast teleport ASAP.
3) Autotargetting the citadel would prevent players from porting back into the fray. This encourages players to buy speed items and discourages running away, since the penalty is greater. It could be solved by making separate scrolls of town portal that autotarget the citadel, or by making scrolls open a one-shot use, 15s duration portal that takes you back out to the front lines.
This is really a separate suggestion, but the generals desperately need indicators in the UI for their current minion counts. I hate having to select my priests to figure out if any of them have died, especially since there doesn't seem to be a hotkey for reselecting your general afterwards.
I feel like units aren't as visually distinctive as they could be. This might just be that my machine sucks and I have the graphics really low, or that I tend to play pretty zoomed out, but most of the units are just sort of blobby. They have distinctive outlines, but when you have a big mass of units you can't see the outlines and its just a blur of color. This might just be my low graphics settings, or that the forces of darkness are colored similarly to the background of Prison, which I play a lot.
Valve's TF2 developer diaries talk about how they used the art style to make edges and units jump out at you very effectively. This is even more crucial in DG where you play so zoomed out.