Straight off, if you like DOTA you will like this game. Of that i have no doubt, but if you don't like DOTA then this may be a nice way to give it a go. League of Legends (LoL) is a free to play with microtransactions DOTA style multiplayer game. In the game you are what is called a Summoner. The Summoner is basically your ID but your profile also gains XP and levels up giving you access to more spells which can be used in game, more runes and rune slots which are a way of customising your hero/champion in the game. It also gives more Mastery Points which are like skill points from any RPG that can be put into 1 of 3 trees that look very WOW like, but for those who aren't RPG fans all of this is given to you very slowly and methodically such that you learn as you go, but not to slow to be a pain for the hardcore.
You then join a game of which at the moment there is only 1 type and you can either do this alone or in a group which is great if you have friends playing the game as well. You then have to choose what you will take into the game starting with your champion. Your champion is your sole unit in the game, you control nothing else. And there is a great amount of choice, if you buy the game you will start off and be able to unlock a lot more of the champions off the bat, but if you go all free to play then very few will be unlocked. However this if anything is a good thing because it means for your first game you will probably just choose the coolest looking one. You also choose 2 spells which are extra abilities such as a heal, revive or smite that can be used and take no mana from your champion. Then you pick your rune set and you are good to go.
The game plays like DOTA almost exactly. For those who haven't before played DOTA, there are 2 teams each with a main base where the other teams objective is to destroy this. Each side on each lane spawns creeps which can be fought for XP to level up your champion, which when you become strong enough you can try kill the other teams champions and towers so that you and your creeps can advance and take down the enemies base. Also back at your base you can buy items to improve and modify your character. Now LoL does a few things that greatly improve this experience. One is that at the end of each lane on either side is an inhibitor which can be destroyed to send a stronger creep which can secure your victory but it is very difficult to get to and destroy this building. Also at the shop for your champion there are 5 suggested items to buy meaning it is easy to jump in and play as a new champion. You can teleport back to your base at any time. And much more that lead to a great game experience. Another great feature is that if you disconnect you can reconnect to a game, which although seems simple is a great addition because 1 less champion on your side of 5v5 can basically make a team lose.
At the end of the game you earn points and XP. The points can then be used to buy more runes and champions. However skins and champions can also be bought with real cash which is how this game intends to make money. I have yet to pay any money but if i really get into it i could see myself buying a skin for my favourite champion. All in all this game is great and free, so there is no reason not to download it and give it a go. Just go to their site make a free account and get going.