local lvl = getPlayerLevel(cid)
setCombatFormula(combat, COMBAT_FORMULA_LEVELMAGIC, -1.3*lvl, -30*lvl, -1.8*lvl, 0)
???
or maybe
local lvl = getPlayerLevel(cid)
setCombatFormula(combat, COMBAT_FORMULA_LEVELMAGIC, -1.3+lvl, -30+lvl, -1.8+lvl, 0)
:D
Not tested but should do something