Syndra's early game mana costs are too much for how little damage she does
syndra does not do significant damage until level 9 (which by then you should have good mana sustain) but before that she is incredibly weak especially levels 1-5 since she really needs her ult+ignite to kill anyone (only after poking them down enough first) but with how little damage her q does pre-9 and the ammount of mana it costs she will likely run out of mana before she can get the target in killing range