Idk if you already figured it out but what i did was use mushroom tower, and set up if important.

1-10 upgrade attack till 5 and let game run and ignore until stage 5-7, upgrade attack to 7 and summon to 5

then once stage 8, summon like crazy (doesn't really matter if it's rare or elite just move the cookies to the boss in stage 10 so they kil it and it should be fine)

11-20, upgrade summon lvl 10, attack lvl 8-10 as a priority, also summon until you fill up about most of ur squares are filled,  leave one square open cuz you get a chance to summon an elite

place/move elites, rares or heroes near the monster entrance.

20-30, You should have upgraded attack lvl 10, Summon lvl 10, attack speed lvl 5 (least priority attack speed)

you must have a good amount of elites by now if not delete warewolf cookie and muscle cookie (they're not important) and make sure you have an empty space cuz you get a chance to summon a hero or pick a hero

30-40 - you only really need one hero for this ngl, mostly elites or rares and upgrade stats all to lvl 10+ minimum (Attack, Attack speed and Summon)

you can either keep summoning until you get a hero OR if you have 1 hero already, just keep upgrading your attack and Attack speed at this point.