If battles become too difficult, try purchasing an upgrade. Be mindful of cost - it's actually more cost effective to purchase a 7-day boost for 15 Power Core than seven 1-day boosts for 5 Power Cores each.
Each Ghostbuster costs 50 Power Core. It's worth purchasing enough Power Core for at least one Ghostbuster so you have a full team of four. This helps make higher difficulty battles seem much easier.
Keep an eye on your abilities and use them frequently. Many of them boost defense, attack, or even heal party members.
Be mindful of where the scientist Ghostbuster is in battle. They have weak defense, so they die quickly, but are vital to keeping other Ghostbusters alive. Better to run away and heal other party members, than to die quickly and leave the rest of your team without help.
1 Energy Point increases every 36 seconds. Remember this means you will have a full energy bar every 36 minutes.
Set reminders on your iOS device for when research on items ends to maximize research potential. Research ranges from 30 minutes to 24 hours, so be sure you are fully aware when one research ends so you can begin another.
Be sure to purchase extra equipment using the in-game cash currency. You'll have more of it than you will know what to do with eventually, so don't be cheap and spend, spend, spend. Use the extra equipment to fill holes in each Ghostbuster's stats. For example, Scientists are weak and have poor defense. Increase their defense to keep them alive by equipping Ecto Vests.
If your team can handle it, always choose the hard difficulty battles. These have the highest cash and slime payouts which help you reach higher floors within the tower more quickly.
Discharge your beam for too long and it will overheat - try to use it only when you know you're definitely going to hit the target.
When entering combat, you have a small window of time before ghosts attack. Use this time to position your Ghostbusters strategically.
Become familiar with the different classes and their strengths. Let the Wranglers take the brunt of the damage while the Scientists heal them. Meanwhile, let the Blasters deal heavy damage to the ghosts.
There are opportunities during combat between waves of ghosts attacking. Use these opportunities to heal any wounded busters and reposition them to take on the next wave.
Many abilities will allow you to quickly heal or damage multiple targets at once.
Be sure to always keep your equipment upgraded so you can take on harder challenges.
If you're having difficulty with tough battles, try using Team Boosts. You can activate them by tapping on the Ecto-2 in the HQ and tapping on the Purchase Boosts button.
Concentrate your fire on singular ghosts to begin with, as you'll need the whole team to take them out quickly and avoid taking damage.
Don't start taking on the hard missions for increased Slime rewards. You'll get wiped out fast if you're not fully equipped.
If you're going to spend the money, buy another Ghostbuster, as having a full squad is the best benefit you can buy early on in the game.