You don't have enough Team Cost because your Player Rank is not high enough yet.
Is it true that diagonal moves are possible?
Yes! It can greatly increase your combo options, but pulling it off consistently is pretty unreliable. It may be easier on a tablet/larger screen. The faster you move the orbs, the more likely a diagonal move will work.
What do I do if I have a lot of stamina left when I'm close to ranking up?
1) Go grind the low-EXP dungeons for evolution materials. 2) If you don't need evo materials, you can try challenging a difficult high-stamina dungeon. If you die, it's no big loss since you can rank up quickly and refill.
How can I rank up quickly?
On weekends when Tower of Giants is 1/2 stamina, "Dragons of the Tower" will give you a great EXP/stamina ratio. If your team is strong enough, you can also run "King of Darkness" in Castle of Satan. For more advanced players, the "Expert" difficulty of Biweekly Special Dungeons are often great for EXP without being very dangerous; please look up the dungeon's corresponding page for details.
I want to use my friend's leader, but he's not in my list.
Have your friend re-login to the game (close the app and open it again), then you do the same.
How do I quit out of a dungeon without dying?
In the top-right, tap the Menu button and select Quit.
Which Normal Dungeon should I run during 1.5x drop rate?
If you're farming for Healer drops, then of course you should do the 2nd stage of a dungeon. If you don't need the Healer, then work on the 3rd stage because it will generally have the highest EXP/stamina ratio. When Castle of Satan is 1.5x, run the last stage (King of Darkness). If you find that too tough, the 3rd and 4th stages are almost as good.
Which Technical Dungeon should I run during 1.5x drop rate?
For any given dungeon, the first two stages are better because Ogres and Demons will be added from the 3rd stage on, which reduces the appearance of Pengdras. Higher difficulty Technical Dungeons have higher likelihood of dropping +1 eggs (plus advanced evo materials), so you should probably tackle the most advanced dungeon you feel comfortable with.
My Loki gives x2 ATK and RCV to Dark creatures and Devils. Does he give x4 ATK and RCV to a Dark Devil-type creature?
No. Leader skills from a single Leader never stack with themselves. However, if you had Loki and added a Harpie Devil to your team (Light Devil), a friend's leader's multipliers to Light creatures would stack with Loki's bonuses to Devils.
My monster has another element icon in the lower right. What does that mean?
These are subattributes, which basically gives your monster another attack when orbs of that attribute are matched. If the subattribute matches the main attribute (e.g. Firedragon Grand Tyrannos), the amount of damage contributed is 10% ATK; if different from the main attribute (e.g. Scorched Claw Dragon, Flare Drall), the damage is 30% ATK.
I was searching on a forum/blog and came across a term/abbreviation I didn't understand.
There is a PAD Verbiage page for commonly used P&D slang. Check there and feel free to leave a comment if you didn't find an answer to your question.