What are some good low elo battle mages?

Swain probably. He's tank, he heals, he deals damage, and he seems pretty straight forward to learn.

Swain.

Make people cry.

Swain top would be the best one for low elo imo

If you don't like that there's still Vladimir and Rumble but you need to learn how to place good ults with him.

And here are my reasoning's.

is incredibly durable , and when played relatively correctly can do some nice burst damage. Also has a nasty teamfight and has good potential to carry. along not traditionally played top lane, can be built durable and is very easy to waveclear with, meaning you can roam and help your jg/mid. Has insane burst, and again a great teamfight. Can be built very flexibly. Full AP, Full tank, Both, whichever you need. Q harass and the utility his E gives makes you a big threat against your laner, has good lane sustain, and brings a lot to the table in teamfights. If you're good at stacking his Q, you can built defensive items first and be insanely hard to kill, then once you hit an offensive item you'll shred. Your E can help you chase and escape, and lets be real.. a 2,000 damage ult is never a bad thing to have in low elo. Deals nice damage and has a big movespeed steroid/debuff, you can also use his R to bait dives and get yourself some easy kills. Not my first pick but if you're looking for something a bit different and team oriented give it a try. can literally be played anywhere, stack your stun and press R and you win again anyone below 1,500 health lvl 6. build rod of ages and protobelt and you'll be an unkillable god top lane.

other traditional picks are

but it's always a good idea to read up on why these picks are effective before diving in with them, as a D5 top main these are my suggestions

Why has no one said Lissandra?! I got reported for going Malz top once, I got so much BM. I don't think Annie is that great top because she will oom fast just trading.

Karthus can be played anywhere as well. His E makes his sustain amazing, and he pumps out enough dmg with his Q making his all in level 2 incredibly strong. You don't have to worry as much about roaming because of your ultimate. Don't use tour ultimate for one kill, his Q does enough dmg and has a short enough CD to where you don't need it for a 1v1. Save ultimate to help other lanes, and practice landing Q's. If the enemy is smart they will stand in the minions to avoid taking double dmg.

Karthus can also be played as a back line Mage doing insane damage with his Q, or in the fight while his E just devours people. More often than not the enemy will focus you in team fights if you're on the front lines, so I like to have a Soraka on my team more than anything else because she can keep you alive.

Vladimir is probably better than swain.

Whereas swain has incredible mana issues, vladimir's resourceless combat and relatively easy to learn combos make him a great pickup for the lower elos.

Vladimir is incredibly hard to master in higher elos where people understand his weaknesses and what-not, but in low elo people have no fucking clue how to deal with vladimir and also usually have no problem face tanking his empowered Qs for no reason.