Talk:Heimerdinger/@comment-4221730-20131102092239/@comment-5068528-20131104055233

They are designed to be a lot squishier early on, to make counterplay possible even by those champions that cannot counter them directly. This requires many to expose themselves to your main harass W, or let heimer zone them with the turrets, so that even those squishy turrets provide heimer with an advantage: the enemy either misses out on creep kills or takes additional harass through laser and W, although not excessively so heimer does not become OP in lane.

From level 9 onwards, they gain significant armor and magic resistance, which makes them more durable in team fights, although their main function is still waveclear and turret sieges. It also depends a lot on positioning, you and your team mates should try not to pile upon the turrets to make them be cleared accidentally by AOE-damage directed to champions. If they're well positioned, they either deal significant damage over time or require focusing by the enemy, which helps too.