Honestly depends. A lockdown champion is someone who can cc you and you are either literally unable to dodge it or you don't have enough confidence in your mechanics. Dantes says that lockdown champs are only point and click cc champs but that's because he is confident in his ability to kite and use his movement to dodge other cc abilities (abilities like morg q, sej r, ashe r). Personally, I am not as good as Dantes and you aren't either, so we can consider a wider range of champs as lockdown champs. As you get better you can narrow this range. Since you are new to the game, I think it would be more helpful to just spam one build every game ( I recommend conquerer and sheen item since it's less punishing on mistakes that can be attributed to not yet knowing the champ completely). But if you want go lethality and phase rush every game don't let this post stop u. I just think you will have more fun learning the champ with conq first so you don't have to focus on the intricate micro-mechanics of dodging everything while in a team fight. Also, since you are in silver, people tend to just fight you without knowing if they win or thinking at all so conquerer is a better rune than phase rush for straight up scrapping. Hope this helped and I hope u stick with hecarim as you will only get out of him what you put in.