I know this might be a crazy idea but....
Can some Mages have that 1 ability that has tank busting stat just like GP E? Having like 60% Magic penetration on that abilities doesn't make a mage burstier against squishy but can fix the problem of having a tank just not ignore mages damage and have to dodge stuff instead of facetanking mages combo.

Watch me regen all the damage by standing still for just 5 sec.


is still incredibly effective since it penetrates 40% total mr. mr gained from items is also lower. and dont forget tanks and fighters just lost 27 scaling mr on runes.