I agree with you.. In my mockups of the UI, there was this concept, that you can trade cards directly as you flip through them.. In this concept by sliding a card upwards with a gesture you would just 'flip' it away. With the steadily increased amount of cards this could become quite convenient. Also, this could be used for TOWERS, POTIONS and ITEMS.
However I really like the horadric cube :-)
Still in terms of usability a change is required in converting cards!
Just thinking it may be cool to have some sort of item called a "catalyst" of each quality level that could be combined with 3 other same quality items to create a same quality potion. Could be much more useful with the new game mechanics as of late.
I had a similar thought. Something like a chance to gain a potion when using 4 rares. Or maybe a level based chance to also create a potion of the same quality as the base items on transformation? On a similar note I've had an idea what to do with Manitou (since that tower is currently extremely boring). An ability like the youtd lich king where an enemy trying to leave manitou's attack range would take damage. This damage would be based on an accumulation of every multicrit performed by nearby towers.
Hmm I quite like Mantiou the way he is already :-) I remember this statement from geX, somewhere in the YouTD forum, where he says that the best towers have a very simple special ability, but still add a lot to the gameplay. I think, his example for such a good tower was Icy Core. But you are right, compared to all other Unique towers in the game Manitou does not do that much.