So, i usualy play elise or karthus mid, and at the start of the match i have about 51 ad, and it makes it very difficult to last hit on creeps. I would end up gettin close leaving the creep with like 1hp... missing out on needed gold, it also becomes a problem when the ranged creeps get pushed to tower. I was going to sacrifice some ap and add AD runes to my rune page, is this a reasonable idea? or does any1 out here have other suggestions? ._. just wish to get better.

You can put 2 points into the mastery at the bottom of the offense tree for 4 extra damage, and you should also try grabbing spellsword. Those mixed with the 2% damage and 5% damage should be enough to reasonably last hit. Sacrificing Mpen marks for AD marks is not worth it.

i remember when this was a problem for me, the secret is just to continue playing the game more, i dont recommend ad runes on most ap mids unless they have steriod like abilities like nid heal AS buff and elise is better with ap imo. The issue you face is something that will get easier with time the more you play mid champs, if you want you can practise last hitting alone in a custom game, i did that for a long time.

If you are using karthus just use lay waste? it takes close to no mana and can do significant damage,.

With Karthus, early game try focusing on clipping singular minions with your Lay waste. Poke minions with AA, and drop it with a well placed Q. Once you get your first few AP items, its much easier to spam Q on the front or back row of minions in each wave.

dont try to rely on karthus' auto attack solely for last hitting-try to work on using his Q to last hit single minions (increased damage if only hitting one target).

yeah karthus q is like a very short cd and cost like 35 mana which is almost nothing q ftw

You gotta use your Q to last hit on karthus

but in this case it sounds like you'd have trouble last hitting with AP carries

Just pick up anivia and practice last hitting

Some AP champions farm better with abilities than auto-attacks. And if you're playing an AP champion that farms better with auto-attacks, there's not really anything wrong with taking AD marks. The gold you get from last hitting effectively is going to scale better than any mark you could possibly put in there.

With Elise, since I see no one else mentioning her, I farm her in Spider form. Spiderlings will help you farm and you don't need to waste abilities with her except maybe her spider q since that makes minions target that target and and it does decent damage. I usually pick up important minion kills with my spider Q or I Q on a siege minion when it is full so the spiderlings know to focus that one. It helps a lot.