fully upgarde a mage and put him in the centre. then get 2 healers and only upgrade them in how much healing damage they do and palce them at the very side. When a game starts move one healer to the corner and dont move the other. that way your healers can heal the mage and when needed, eachother. It got me to lvl 5. I would have gotten farther but I accidentaly moved my mage off the centre.