User blog comment:RoznosicielCiast/Least popular champions/@comment-5185239-20130125022429/@comment-216.36.26.248-20130125061757

This, pretty much.

Heimerdinger, Karma, and Trundle can be played well and wreck his lane. The same could be said of any champion. The problem with all three of these, especially Karma, is how bad they get outshined by everyone else.

As a top lane, Karma is still plenty squishy against other top laners and has a hard time living the bruiser lifestyle. She'd have to use her Q often to heal herself. Which, by the way, it's not very good at. A fixed heal with higher base/scaling would have been better. It being AOE is nice, as not many champs get AOE healing skills, but not enough to redeem its low healing amount. She also shows the whole world how many Mantra charges she has so people know when you just burned your second one and when to pressure. This would drastically reduce her effectiveness in pushing as she can't use her bubble damage to push.

In the mid lane, she fares best. Her early game pushing will catch people by surprise but you'll still have trouble pushing against other AP Carries that can do the job. You will likely win your lane if you don't die to ganks or have an opponent with strong AOE. You'll want to build some CDR as you have rather short cooldowns but nowhere near the burst or sustained damage of most mids. The bulk of your damage will come from her Q.

In bottom lane, Karma is detrimental to the team. Most of her skills are AOE which leaves her unable to have much effect without pushing the lane. Her heal is weaker than other healing supports and it can be a struggle to use it without pushing the lane. Because she has no good CC, once team fights break out she has no way of neutralizing anything. Soraka has silence, Sona, Nami, and Taric have stuns.

tl,dr:

Karma is not too bad in mid lane, but is out classed by real AP Carries and AD Assassins. Everywhere else is between bad and detrimental.

Six ranks on three skills is not a benefit. It means you can't max a skill until 11, when other casters have had their first skill at max since 9.