Tips for tower events can be found here.
Angry #167, 3 pieces, last piece costs 250 coins
Dark Cave #608, 4 pieces, last piece costs 1000 coins
Pythoness #1083, 5 pieces, last piece costs 2000 coins
Blood Mage #1156
We start with 125 coins + 600 coins every 8 hours = 5525 coins
Hopefully we will get a coin quest and additional coins from freebies.
Check this for collectingtimes.
The map shows they way to the top (blue line). The orange line is the way to the ticket.
If you collect the ticket you can choose one of these dragons 24 hours after the event ended:
Chibi Chomp #1092
Grapple #1022 or
Pro tip: Wait until the last collection is done and then check in flightmode how far you can come.