1. Exp gain per hit (dmg done)
Bring many changes... Now 1 tower grow all another just being here..)
2. Challenge waves explore your weaknes.
If u have 1 strong tower you meet tons of spam creeps. if you grow gold bins meet 1 huge beast armored & slow. On bonus round >1700 sec i all time swap last item on my carry (arm pen/splash/range).
3. Some item shop.
My last try: i hold all items & tower up to 101 wave. To transmute in to wrath set. Then i just skip waves up to 200. When i reach bonus rounds i realize that dropped only 1 life pot... & my carry have 48% of item drop & qiality.... Gods of random hates me...) reached 1300 sec...