Free: 0 Stars – Paid: 5 stars. Free: 30 of the worst ads every day. Most over 45 seconds, multiple clicks to close, opens the app store before you can close the ad, Multiple counters, hidden close buttons, some open web sites. Grind time is massive! Paid: fun, wide variety of towers, runes and heroes. Mobs are pretty good. Maps are limited. The boost from paying gives you a lot better rewards for everything and makes it possible to upgrade the towers, spells, and heroes.