I don't know if these have been suggested but:
1. A way to share energy? if u are feeling a bit used, then you don't have to share.
2. The "Play solo!" option in the dungeon information window to be that u make a solo games and only your friends can join, meaning that you dont have to keep inviting and inviting?
3. A "blood pack" machine in the beginning of each dungeon? like the enhancer/elixir vendor in PL/SL in case you waste all of your blood packs by soloing or.. just not the team you would expect.
4. Lastly, let the buffs you get only be used up in dungeons? meaning they don't stop while you're offline.