Hey Player J, since you clearly don't get it here, I'm going to flat out prove to you that Tomb Lord is inferior to other def down champions of lower rarity in a way you CANNOT refute...
Here is my current roster:
My current arena team is: Nethril (TM reduction and stun), High Khatun (for speed aura and TM boost), Bystophus (lockdown and def down), and Inithwe (hard hitter and finisher with A2).
YOU go ahead and pick who to pair up Tomb Lord with, and I will compare him in the same exact group and similar (or same exact) gear on Tayrel, and you can see firsthand how big of a difference there is between the two. You can watch the damage Tayrel does along with a more frequent defense down compared to Tomb Lord, while Tomb Lord misses most the time and does NO damage. Then, you can see what I am talking about.
Nethril and Khatun cannot be replaced. Nethril has max speed gear on him for TM reduction and stuns at the start, and Khatun is for speed aura and TM boost for the other slower champions. So, you MUST pick a team where those two are involved. I am not going to take a bunch of losses in arena just to prove what I already know firsthand. If you don't understand, watch some of my latest arena videos in my channel with that arena team and you will see how they work.
Personally, I would suggest keeping Bystophus over Inithwe, but since Bystophus has his own defense down (which combined with skill lockdown is FAR more valuable than Tomb Lord), it would probably make more sense for me to replace Bystophus with Tomb Lord so that it won't skew the comparison. However, so you can't whine that I "picked the wrong group" you go ahead and tell me exactly who you think the other champion should be paired with Tomb Lord?
So, it will be: Nethril, High Khatun, Tomb Lord (and then Tayrel as a control subject), [your pick].
Once you pick, I will make a video of multiple encounters on the same tier in gold. At least 10 battles with Tomb Lord in that group, and then at least 10 battles with Tayrel in the group instead of Tomb Lord. I will make sure to take on comparable power levels on opponents and make everything transparent through the entire video. I will PROVE to you that you have absolutely NO idea what you're talking about here irrefutably with a video, just to quash your naivety ;)
So, balls in your court kid. Name your poison and I will put the video together and show you how you have no idea what you're talking about and why looking at a champion in game does not compare to the firsthand experience.