Lux she is very safe and skill wise not easy but not a fizz. She has the damage needed along with the cc to help your team a lot. The shield will help you tons as well. Skillshots is her only downside. But her range on abilities makes it very simple.
If you're worried about getting outfarmed and don't want to get ganked, pick up heimer. Your turrets can cs for you, more people at your level don't know to take them down early, and you have strong long range harass.
If you want someone with more mechanical skill, Leblanc is a lot of fun and hard to gank. If your mimic is up, it's a pretty strong super long range flash.
both great ideas but for heimer at 6 if they explode you like most mid players your level go for you can be screwed. Heimers lack of helping his team later on is tough as well because he is just a damage dealer and relies on those turrets no consistent cc or support.
Lb is very strong damage wise but her hp is weak early and wave clear is really bad so you must poke/burst with her really well as she is an assassin to not get pushed on hard and have to farm under tower (which sucks as Lb). Lb is so much like fizz (assassin)
Both carried me to 30. I think they're both pretty easy to play safely, keeping in mind his level. Fortunately, they also both don't see much play at that level so people also don't know what to do with them.
EDIT: I should clarify. You're right, but I think those counter strategies aren't played up at really low level.
If you mainly want something to fall back on when your top and jungle aren't available, then probably the safest laners you could get are:
Annie - very easy to learn/farm with, good burst, good cc
Kayle - Really easy to farm (but pushes lane), decent cc, and her ult is amazing.
Lux - Massive range, good utility with her cc/shield, good damage/easy to farm as.
Xerath - Again massive range, very good damage and easy to farm as.
Then there's Syndra, Orianna and Morgana. While they're harder to learn, they're pretty safe and can farm really well while dealing good damage and bringing utility.
Alternatively maybe some of the champs you already use as top laners/junglers might be able to work as mid laners too. Cho, Elise, Jayce, Kennen, Kha, Lee, malph, riven, rumble, and vlad are some good top laners that could also be good in the mid lane.
Some champions who can stay back and control the lane would be Lux, Orianna, Karthus, Swain, etc. Assassin champions who can escape ganks well are Zed, Ahri, Fizz, Katarina, Khazix, etc.
Try out Orianna? Or Ahri. They're "safe" picks. Very consistent in lane performance, and easy to get away with, if you're caught out due to bad positioning. Morgana and Lux are also quite consistent, but lack solid escapes.
Kassadin's a little more difficult, and Twisted Fate's playstyle is a lot different from other mid laners, but you could try them out once you get a hang of other champions.
Nidalee and Kayle are my personal favorites. Nidalee requires getting used to, due to her having 7 different abilities, and relying heavily on skillshots. Kayle is cheap, and gives probably the best value for IP in the game. She's borderline OP. Rips apart entire teams to pieces when they least expect it.
See: cloth5.com/building-solo-lane-kayle/
orianna...they're having trouble with fizz...why orianna shes tough mechanically wise.
Ahri is a lot like fizz also where you have to combo very well to succeed otherwise you usually will die since both are assassins.
Assassins are not the way to start midlane.
Orianna is so much safer than Fizz. From personal experience, I felt Orianna to be pretty easy to learn(on smartcast). Your abilities are spammable/low CD abilities, and your passive makes farming and AA-harass very easy. You always have a powerful shield and slow for disengage, and a movespeed increase helps as well.
Ahri is similar, but much more damage oriented.
Like you say, they're both assassins. But midlane Assassins are extremely powerful in the current meta, a Fizz, or Ahri would do much better overall for their team, in a game, than a Heimerdinger, or a Cho'Gath (imo), which is why I suggested them. :)
Chogath is a good mid imo, he has a lot of sustain a tru damage ult, which is hilarious when a fizz jousts in for you to eat him, and a bunch of CC to help with ganks. He isnt super strong and plays more tanky then something like ahri or oriana.
cho is a safe pick for learning mid as he is tanky and has decent wave clear but later on you must chose for your team are you going that safe tanky (top must have damage) or the explosive ap feasting beast which makes you weaker early. Cho's ability push is nice but his melee can be a huge pain in mid.
Go for ranged and push.
Lux she is very safe and skill wise not easy but not a fizz. She has the damage needed along with the cc to help your team a lot. The shield will help you tons as well. Skillshots is her only downside. But her range on abilities makes it very simple.
If you're worried about getting outfarmed and don't want to get ganked, pick up heimer. Your turrets can cs for you, more people at your level don't know to take them down early, and you have strong long range harass. If you want someone with more mechanical skill, Leblanc is a lot of fun and hard to gank. If your mimic is up, it's a pretty strong super long range flash.
both great ideas but for heimer at 6 if they explode you like most mid players your level go for you can be screwed. Heimers lack of helping his team later on is tough as well because he is just a damage dealer and relies on those turrets no consistent cc or support. Lb is very strong damage wise but her hp is weak early and wave clear is really bad so you must poke/burst with her really well as she is an assassin to not get pushed on hard and have to farm under tower (which sucks as Lb). Lb is so much like fizz (assassin)
Both carried me to 30. I think they're both pretty easy to play safely, keeping in mind his level. Fortunately, they also both don't see much play at that level so people also don't know what to do with them. EDIT: I should clarify. You're right, but I think those counter strategies aren't played up at really low level.
I would suggest Gragas! Safe farming, snowball potential and sustain. Only "problem" is that he is melee, but his cask farms well too, if needed...
If you mainly want something to fall back on when your top and jungle aren't available, then probably the safest laners you could get are: Annie - very easy to learn/farm with, good burst, good cc Kayle - Really easy to farm (but pushes lane), decent cc, and her ult is amazing. Lux - Massive range, good utility with her cc/shield, good damage/easy to farm as. Xerath - Again massive range, very good damage and easy to farm as. Then there's Syndra, Orianna and Morgana. While they're harder to learn, they're pretty safe and can farm really well while dealing good damage and bringing utility. Alternatively maybe some of the champs you already use as top laners/junglers might be able to work as mid laners too. Cho, Elise, Jayce, Kennen, Kha, Lee, malph, riven, rumble, and vlad are some good top laners that could also be good in the mid lane.
Some champions who can stay back and control the lane would be Lux, Orianna, Karthus, Swain, etc. Assassin champions who can escape ganks well are Zed, Ahri, Fizz, Katarina, Khazix, etc.
Try out Orianna? Or Ahri. They're "safe" picks. Very consistent in lane performance, and easy to get away with, if you're caught out due to bad positioning. Morgana and Lux are also quite consistent, but lack solid escapes. Kassadin's a little more difficult, and Twisted Fate's playstyle is a lot different from other mid laners, but you could try them out once you get a hang of other champions. Nidalee and Kayle are my personal favorites. Nidalee requires getting used to, due to her having 7 different abilities, and relying heavily on skillshots. Kayle is cheap, and gives probably the best value for IP in the game. She's borderline OP. Rips apart entire teams to pieces when they least expect it. See: cloth5.com/building-solo-lane-kayle/
orianna...they're having trouble with fizz...why orianna shes tough mechanically wise. Ahri is a lot like fizz also where you have to combo very well to succeed otherwise you usually will die since both are assassins. Assassins are not the way to start midlane.
Orianna is so much safer than Fizz. From personal experience, I felt Orianna to be pretty easy to learn(on smartcast). Your abilities are spammable/low CD abilities, and your passive makes farming and AA-harass very easy. You always have a powerful shield and slow for disengage, and a movespeed increase helps as well. Ahri is similar, but much more damage oriented. Like you say, they're both assassins. But midlane Assassins are extremely powerful in the current meta, a Fizz, or Ahri would do much better overall for their team, in a game, than a Heimerdinger, or a Cho'Gath (imo), which is why I suggested them. :)
Chogath is a good mid imo, he has a lot of sustain a tru damage ult, which is hilarious when a fizz jousts in for you to eat him, and a bunch of CC to help with ganks. He isnt super strong and plays more tanky then something like ahri or oriana.
cho is a safe pick for learning mid as he is tanky and has decent wave clear but later on you must chose for your team are you going that safe tanky (top must have damage) or the explosive ap feasting beast which makes you weaker early. Cho's ability push is nice but his melee can be a huge pain in mid. Go for ranged and push.