This is one of the tougher tower defense games and features 6 types of towers with 5 types of attacks. The creeps can be resistant to one or more types of attacks so you’ll need to have a variety. In this game, seeing which type of attacks the next wave of creeps is strong against is crucial to victory as you will need to upgrade according to whichever type of attack the next wave is weak against.

Starting tower placement is very important as there are generally two spots you’ll want to place your towers. It is much better to group your towers together in one of these two spots rather than spread them out all over the map as putting them together will lets you take advantage of their combined effects far better. The stone tower can only hit one target a once, not multiple targets(unless you get the feature upgrades) and each type of tower can be upgraded far more than six times(the six times is for features, not for damage). The two starting spots are the two island spots that are surrounded by the path, you’ll want to place all your towers in one of these two positions. I can’t say which one is better but I like the top island the best since its smaller and I can position my towers so they hit more of the area around the path. You also need to check the range of the towers to place them in the best spots. You need one of each kind of attack tower. I prefer to combo the stone, ice, earth, fire, and poison so I have one of each attack type. Don’t forget there are two types of upgrades available, upgrades for the feature, and upgrades for the tower itself in terms of damage, you’ll need both, especially for the stone towers. Because each additional tower of the same type costs more than the previous by a lot and upgrades are only incremental in expensiveness, I recommend you only build one of each tower type(choose between stone and sharp would be my advice since they are both physical) and stick with upgrading those as this method is far more cost-effective than anything else. Try to keep all your towers at about even level, although you will have to adjust depending on the resistances of the creep waves. In terms of features, I find that the most important feature upgrade is the stone tower as that gives the ability to hit more than one target so you’ll want to upgrade this quickly. I’d focus on the features of the stone and the ice tower and do the rest when you have time. The earth tower’s AOE generally kills all non-earth resistant types for quite a while and if you upgrade the stone tower’s feature, it will kill most that have earth resistance but not armor resistance. Remember to upgrade ice, poison, and fire too as no creep has high resistance against all five. You could be fine with four damage types also but I prefer five to be safe.

For the initial build, I’d build a stone first, then a poison, followed by ice, earth, and then fire. Then I would just upgrade damage until about level 4 when I would start upgrading the stone tower to hit more than 1 target. I would try to max this feature when I am not upgrading damage for the other towers. Features are nearly as important as the damage itself because it will give more slow, lasting damage over time, and multi-shot abilities. If you place all of your towers on that top island in good locations and just upgrade features and damage as explained here. You should be able to beat medium with room to spare.