I didn't read through all the other suggestions that were posted before my suggestions, so it might be possible that I 'steal' suggestions from someone else. If that happens, I'm sorry for that, but I won't delete them, because, after all, we all want a nice Tower Defense update, right?
Mobs
There are a lot of unbalanced mobs. Some need to be buffed, some need to be nerfed. Here I will explain which mobs need to be buffed/nerfed. (Clarification: Buffing a mob means making a mob stronger, nerfing a mob means making a mob weaker.)
- The Skeleton needs to be nerfed. The damage it deals to the towers and its speed is okay, but it has too much HP. Right now, when the enemy starts spamming skeletons at the start of the game, there's no way to stop them. Mages? They are invulnerable from level 4. Turrets or AoE potions? Forget about it. TNT and archer towers seem to be the only possible way to stop them. But TNT and archer towers are quite expensive, especially at the start of a game.
- Buff Creepers. I remember that, when I first started to play the game (just after it was released on this server), creepers were the meta. They had a lot of HP and despite being slow, they could regenerate so their speed wouldn't really matter. But right now, I consider creepers the worst mobs of the game. They are very expensive (300 coins) which makes them pricey to buy at the start of a game. But at the middle/end of a game, they become useless because they don't deliver enough experience to upgrade your goldmines/troops (45-66 exp), and because they don't have enough HP to actually deal damage to the castle. Its speed is fine, but its HP should be buffed just a little and the damage it deals should be multiplied by 1,5. I mean, we're talking about creepers that explode everything that stands in their way, instead of cute little kittens that accidentally scratch you every now and then, right?
- The Giant should also be buffed. It is extremely expensive and it should be the 'strongest troop', and yes, it has the most HP and deals the most damage, but if you have a decent defense (think about a lot of Sorcerers, some rows of Archers and TNT towers, etc.), this mob will never reach your castle, if not maxed out, which is almost impossible. The giant should be a little faster, it should not have more HP and it should not deal extra damage, but since it's very underpowered for such a high price, it should be buffed in some way. And I thought of a way on how to buff this huge zombie! Every tower should deal less damage to a Giant, so its HP wouldn't be affected, but it would be a lot stronger. The zombies it spawns after its death should also become stronger. Maybe you could add more HP and speed to the zombies so that they aren't completely useless. Conclusion: Endgames take too much time and Giants should be the deciders of the game, and currently, that's certainly not the case.
- You should also buff the Silverfish. It currently is so weak that nobody uses it. It has no use other than being a small distraction in the beginning of the game. It does not give you a lot of experience (18-22 exp), it only has 180 HP (at level 1) and it deals only 1 damage (at level 1). It isn't fast, since its speed is 1.6, which is an average, normal speed when it comes to the speed of tower defense mobs. Although it is able to fly, this mob is just too weak. Either remove it or buff it, but please don't let it stay the same.
Towers
Some towers are fine (in my eyes), but some are a little unbalanced. Here I will mention what needs to be changed.
- The first path of the Zeus tower needs to be buffed a little. I don't think anyone uses that path because the lightning bolts are just not strong enough. If you name a tower the 'Zeus tower' and make it pretty expensive (1000 coins), people expect it to do awesome things. And if you think of lightning you think about a strong bolt that kills everything on its way to the ground. But currently, the lightning bolts it produces just tickle the mobs they hit.
- The Ice tower is a little underpowered in my eyes. I think it should slow down and stun the mobs more, because it should actually freeze the mobs. And the ice damage it deals at level 4 should also increase, because although the tower is cheap, it should be a lot stronger.
- The Archer tower is too strong against every mob. Both of its paths need to be nerfed a little, because full waves of blazes, giants, any troop you could imagine, get taken down. It's just a matter of seconds, even in the endgame. In my opinion, its price is fine but it should be just a little bit weaker.
Other must-haves
- Although I haven't read every suggestion here, I did read Story's suggestion about people placing towers in the wrong spots, and I personally think his suggestion must be added. It is so annoying that every time when you join a game, someone who doesn't understand the game or a troller is on your team and ruins your game by placing towers in the wrong spots. And in the worst case he or she can't speak English, so warning or correcting them is impossible. I know you can report people for this but preventing something is always better than letting others suffer because of these players. So please make players unable to place 3x3 towers in 5x5 spots.
- I think we should be able to share experience with our teammates. I oftenly have tons of experience and don't know what to do with it, while others could use to in order to upgrade their mobs or purchase AoE potions. I think the 'old' sharing command (to share coins) should become /share coins {player} {amount} and the 'new' command (to share experience) should be /share experience {player} {amount}.
- The armageddon modes should be more threatening. The lightning armageddon mode is just completely useless, because the wither mode also destroys towers with its skulls and it even deals damage to the castle. (And it is a great tank) The horde mode is also very weak because it doesn't spawn strong mobs; if you join a game with double income and the horde armageddon, you don't expect to get 2 level 3 Giants against you if the information states that the mode will spawn very strong mobs. So, maybe the horde could stay the same in the normal pricing modes (so without double income), but when double income gets selected, the mobs become stronger, so it would become a real threat to your castle. Conclusion: The wither mode is moderate, the lightning mode needs to be either replaced or buffed, and the horde mode should be buffed a little in the normal pricing games, and it should spawn stronger mobs in the games with double income selected.
I hope you'll do something with my suggestions!