i strongly feel champions should not exist that counter a damage class (rammus, malphite)

rammus, malphite, to a lesser extent kassasin and veigar counters AP

rammus and malphite are the biggest offenders

malphite takes no damage from physical. and is so tanky he barely takes damage from magic too

to balance out rammus id do something like this. instead of damage return on autoattacks, rammus simply will return 5% of damage taken (before resistance calculated) with his armor mode

and for malphite, i would balance him to get extra MR+ARMOR instead of just armor (but less of both). and id give mr+armor scaling to his spells instead of just armor scaling

for kassadin i think he needs another rework. hes too much antimage, not enough voidwalker

for veigar, id consider his kit sort of toxic too. hes actually strong and if the enemy hes a AP midlaner his R is kind of like too strong. but its ok because in a teamfight veigar wont get past the tanks to press R on the enemy mage