Currently the most challenging levels are ones with multiple paths to the goal, since there seems to be some expectation you'll have heroes that can attack universal targets. I have plenty of allies that can attack anywhere on the map but are ineffective vs. MOABs or lead Bloons. Of course the game recommend buying a DLC hero for this but I welcome the challenge of working around it. Just got a legendary weapon for Pirate Cassie that just deletes everything on the stage once every three rounds. Feels a little OP but made extreme mode a breeze on any maps that allows water heroes.
Your biggest power spikes come from epic and legendary items, which can both be received from pink loot orbs. Easiest way to get those items is completing stages on extreme difficulty from the chest. The difference between having those items and not are insane. Some examples: Epic Rattleballs ally can single handedly clear the final wave in hard mode minus the lead bloons. Legendary PB gun boosts attack speed by 60% and piercing by 6. Legendary Max weapon gives him extra damage and another dart and piercing. Having just a single epic or legendary can allow you to clear multiple levels that were impossible before acquiring it, so focus primarily on getting to extreme and rolling pink loot orbs until you get a legendary item.
I tried and tried to push through and I do feel like I got $5 worth of time out of this but it's going backlog for now. It seems like they are trying to innovate a bit on kingdom rush with heroes and what not and I like the thought but it's too money hungry for it's own good the way it stands, I never felt like I had to grind in KR for anything or defenders for that matter and I just can't justify anymore time and certainly not anymore money. With games like KR and Teen titans proving that one time premium with only optional purchases and never invasive(like losing and being told the strongest heroes are only $10 away) makes this a backlog and possible delete if some of this isn't fixed. I pushed Lucavious on his thoughts on IAP and I'm big enough to admit there were some very valid points there.
So I played the game more and I have to correct myself: you can finish most of the maps without buying if you are willing to grind. The game throws you enough freebies with achievements so you can progress until there are no more achievements. The issue I have with this game is that the strategy part of the TD is non-existent: to progress you just grind until you get better items. Even on the maps where you are supposed to be smart about placement (I.e. the ones where Bloons take different paths), it is a better strategy to keep your towers grouped up at the beginning or end and then grind until you can pass them. Also once you run out of achievements, I is very hard to progress as crafting an epic costs 3500 shards and they are not easy to grind. The other issue with items is that there is not much replayability (except for grinding): as you upgrade characters, past levels become too easy so you have no troubles clearing them anymore.
I've finally stopped playing and I'm changing my rating from 3 to 1. The effort they put into robbing players significantly diminishes any fun you might get out of it. 1) Still forced to watch ads after paying to remove them just so Ninja Kiwi can get a few more pennies from you (you can only avoid them by flushing loot down the toilet). It's incredibly irritating that they water the entire game experience for such a tiny monetization scheme. 2) So. Many. Bugs. It wouldn't bother me if the game didn't delete all your money and beg you to buy more after the bugs steal it all. Bloons fly to the exit without getting chased by your chase heroes, game crashes due to over-use of zombie bloons, abilities that actually help the enemy like Jake's inhale, etc. and there's nothing to protect you from losing all the gold you earned from it. You just never know when that 2,000 gold you spent will get tossed in the trash by a random bug. 3) There's no strategy. Just luck. One item I got deletes the whole level every three levels. If you don't get that item you're playing a harder game than everybody else. If you can't beat a level you just buy loot until you can. Just can't deal with it anymore.
