First of all, let's make some things clear:

-I'm NOT challenger
-I'm NOT a Pyke main
-You can argue with the build/runes, but this is my way of playing the champ.

Just read the full guide, try it and draw the conclusion.

The main points of the guide:

- You are not paper even if pyke has low health pool.
- You can play it well even if you can't hit spells. (No point in buying lethality if you dont hit any spells or you get delted in a second)
- Your AD is almost the same as it is with full lethality, but you are tankier than any other tank champs in your team (most likely, but ofc u can't outscale a rammus or something like that)
- Pyke's R is true damage, an execution, so it doesn't need any lethality to be useful, and since your AD is almost the same as with lethality, your ult's "execution hp" won't be much lower, just a little bit.
- Transcendence will give you AD based on your CDR, and as you see this build is way more than the 40% limit, you will get 48 AD on full build. if you use my guide.
- Gathering storm will give you more AD as the game gets longer and longer: HIGHER HP TO EXECUTE
- Spirit visage will help you heal more with passive, you can even buy it vs full AD too, its a must have item honestly. Revitalize will help you heal even more.
- Frozen heart will reduce attackspeed around you, with this build you can jump in without even thinking about dying.


(stats change with build, but this is with my most common build)

Comparsion:

CDR Tank build:

20 minutes, lvl 18 stats:

AD :326
Armor :260 ---->+aftershock bonus
MR :188 ---->+aftershock bonus
Transcendence: 48AD
AD bonus from passive: 92
Ult damage:550+197+86
Tenacity 48% with Mercury's treads + Elixir of Iron (All cc is shorter on you if someone didn't know)

Lethality build:

(With mobility and full lethality, the usual build + Eletrocute rune)

20 minutes, lvl 18 stats:

AD :383
Armor :130
MR :58
Transcendence(if you have it with the electrocute rune):12 AD
Passive bonus AD: 71
Ult damage: 550+208+86
Tenacity 25% (only if you buy elixir of iron)


I know people use lethality in challenger, I heard it a lot, but as you can see, they have something like 5 kills overall at 20 minutes, because they CAN play.
Most of the players I see are NOT challengers, and they can feed up to 10 deaths in 20 minutes or more and thats just 1 person's death counter, not 10 like in high elo. So consider these when you think trying to follow pro players will make you better at your own rank.

Please give it a try and good luck on the rift!