Spellspire
22 Achievements
Star Tower
Complete star challenges for each of the floors.
5.2%
How to unlock the Star Tower achievement in Spellspire - Definitive Guide
Stevenjameshyde
Completing a star challenge requires you to complete a level with full health. Monsters strike 10% faster when you replay the level for the star challenge, but otherwise the levels are identical. You will probably find yourself completing most levels without taking damage when you complete them in normal play, especially if you follow my recommendation of spending all your gold on attack power rather than health upgrades.
Note that 'finish with full health' is not the same as 'don't take damage' - if you get hit, you can consume a healing item just before you kill the final monster and still complete the star challenge.
Stevenjameshyde
Completing a star challenge requires you to complete a level with full health. Monsters strike 10% faster when you replay the level for the star challenge, but otherwise the levels are identical. You will probably find yourself completing most levels without taking damage when you complete them in normal play, especially if you follow my recommendation of spending all your gold on attack power rather than health upgrades.
Note that 'finish with full health' is not the same as 'don't take damage' - if you get hit, you can consume a healing item just before you kill the final monster and still complete the star challenge.
Necrophage33
This takes place in the tower. As soon as you finish a floor, you are then able to replay that floor to earn a star. The star challenge is exactly the same on every floor: you have to finish the floor while at full health, and enemies move 10% faster. NOTE that this doesn't mean you can't get hit. If you have a potion handy, you can heal after getting hit, and you'll still get the star as long as you have full health when you kill the last enemy.
In general, you're going to be following the strategy lined out in the "Dragon Slayer" achievement solution for progressing through the tower and replaying floors. Since you'll be buying new stronger wands as you go, this makes it very easy to replay levels and beat them at full health. I was able to beat every floor without every getting hit and with only buying a new wand every 20 or so floors, so this is easily doable. Most items you get are pretty useless in battle and sell for practically nothing in the shop, so once you get a potion or two, just keep it in your pouch so it's ready in case you do get hit. Then you can quickly press 
to heal and won't miss out on the star.
The only spots that can be troublesome are ninjas, since they attack very quickly, and the dragon at the top since he has so much health. For the ninjas, save your 6+ letter words for them so you're guaranteed to take them out in one hit so you don't have to worry about them attacking you. For the dragon at the top, you really should have 1-2 health potions in your pouch for this fight since it is highly unlikely you'll be able to do enough damage to him to kill him before he can get his first attack in. There is also a hat that starts you with an arcane shield which blocks the first attack you take, so this gives you double the time to attack the dragon before he does damage to you.
Playing through all 100 floors again will take a while, so it's definitely better to replay them as you go to keep making money to afford new wands for new bosses.
Once you've gotten a star on all 100 floors (indicated by the gold floor number and a star next to it) the achievement will unlock.
