Item builds are more fluid but there won't be anything game changing. No sheepstick no bkb no blink dagger (there's a summoner spell for it but it isn't nearly as versatile) no refresher stone etc. Basically it comes down to which stat (attack/magic/hp/mp/armor/ resist) you want for your hero and piling that on.spermatic cord said:
Last hitting is less important since you have a lot of gold coming in regularly. Can't deny creeps, towers, and as far as I know no hero skill let's you deny a hero. Also a tower kill gives the same gold to your entire team no matter who kills it.
Runes are replaced by extra strong creeps that give you a buff (mpregen + cooldown reduction or dot + slow), two to a side.
A lot of skills involve aiming and there are generally less stuns than in DotA/HoN. Most fights are a tug of war. Skills are more spammable, natural mana regen and health regen are quite high early game but their use really peters out to at mid game.
Towers won't attack you if you attack them. They'll only attack you if:
1) You attack an opposing hero while in range of tower
2) You are within range of tower and no other creeps are nearby.
So basically while it's your job to guard the tower in HoN, in LoL the tower is more active in guarding you, but less concerned with taking care of itself.
You don't lose gold upon dying so don't be afraid of stockpiling money for that big item. A few kills won't make you fed. You'd have to go like, 7-0 to really start dominating and even then a competent team will be able to shut you down. Carries are less of a threat in this game and having good teamwork is a lot more important.
Just play some games and get used to the slower pacing. If you were any good at HoN and you should do fine,
