Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is all you'll need
D5 Hecarim main here, this is what I used to climb this season. Started season Bronze 2 (Went 2-8 in placement matches, Gold S5, Plat S4) and was able to get to D5, trying to get to D4.
I'll try my best to respond to any questions you may have as I know this is a barebones guide.
Rune adder not working properly.
9X Armor Seals
9X Armor Pen Marks
9X CD Blues
2X Movement Speed Quints
1X CD Quints