I Think MANY Fans Agree When I Say This.. This Game Is Fun, Somewhat Addictive.. BUT, It Doesn't Have Nearly Enough Features Or Depth For Your "Store" To Be Purely P2W Currency. Switch Everything to Coins, Except Charms.. Thatd Be Awesome!
Pressing The "Manual/Auto" Button.. Should have it strategically place units for you, instead of leaving one row empty while the enemies walk straight through to your hero.