When playing zombies gamemode you will have to choose a class and my suggestions are:
Always to choose summoner class: if you don’t know which one is summoner class you can always switch your class in first round:
Why is the summoner class the best:
Because his upgrade is always op and also his armour sets you may get from armour chests around the map, along with wips and sentries that will get more op by upgrading
I personally think the mages get absolutely let down by their weapons (on most maps,not all),like for example one time while playing on a map tier 1-3 or 4 idk was all wand OS sparking that just added like maybe 3 additional damage per tier and with the amount of zombies you had to deal with,with only 20 mana is ridiculous