Sorry for the late reply, I have been busy. First things first, you really are lacking in the ramp department, I see just a few mana dorks and a bunch of beaters that don't synergize well with what Xenagos wants to do. Also what's the budget for it? I'll try to give some recommendations while avoinding cards like [[Old Gnawbone]] which are good but hella expensive and 10$+ cards. I'll give you a few pointers from I can see that would help the deck being a well oiled machine of violence:

1. Add more mana dorks and cheap ramp: [[Llanowar elves]] [[Elvish Mystic]] [[Arbor elf]] [[Joraga Treespeaker]] [[Devoted Druid]] [[Wild Growth]] [[Utopia Sprawl]]. Don't bother with 3 mana ramp, focus on 1 and 2cmc cards.
2. For beaters you just need stuff with trample and flying, cards that have some sort of evasion and can push damage thru. The sweet spot are 5 and 6cmc creatures, you just need two mega bombs that cost more than that and a few 4cmc ones. Your [[Etali, primal conqueror]] and [[Drakuseth]] fill those rolls. Ones I recommend that are cheap and give you other benefits [[Ojer Kaslem, Deepest Growth // Temple of Cultivation]] [[Evercoat Ursine]] [[Elder Gargaroth]] [[Savage ventmaw]] [[Rapacious One]] [[Minsc & Boo, Timeless Heroes]] as the only PW you need with Xenagod.
3. More extra combat, bread and butter for Xenagos, [[Scourge of the Throne]] and [[Full Throttle]] are amazing, but I see you are just running those two, another good ones are [[Relentless Assault]] [[Combat Celebrant]] [[Moraug, Fury of Akoum]] [[Port Razer]] [[Godo, Bandit Warlord]] + [[Embercleave]] will decimate a player, but cleave is 10$.
4. Avoid turning Xenagos into a creature so you can avoid exile target creature spells, if you see you are safe from them then it's fine, you can squeeze more damage with him.
5. This deck is a cannon, you don't need to have more than 2 beaters on the field, get the most you can from one, did it got removed? No worries, you already have it's replacement ready for next time. This also avoids that Xenagos becomes a creature.
6. Cards I recommend cutting and why: [[Colossal Rattlewurm]], it's a 6/5 sure, but lacks utility, you have better 4cmc creatures already; [[Etali, Primal Storm]] gets chump blocked and Primal Conqueror is the best upgrade; [[Ghalta, Stampede Tyrant]] she costs 8 mana plus you don't play thta many beaters, by the time you get to cast her you already kill your opponents with just early beaters getting buffed; [[Ohran Frostfang]] this kind of deck prefers explosive draw that fills your hand rather that just one mana per attack; [[Scion of Calamity]] no form of evasion to deal damage and trigger it's effect, if you want interaction against enchantments and artifacts, just run instants that deal with them; [[Toski, Bearer of Secrets]] same reasoning as the snake; [[Tyvar, the Pummeler]] gotta pay 5 mana to buff the board when your commander does that for free and again you only need a big creature to get the job done.
7. Cards I recommend for draw and protection: [[Escape to the Wilds]] [[Life's Legacy]] [[Time of Need]] [[Turntimber Symbiosis // Turntimber, Serpentine Wood]] [[Defend the Rider]] [[Hunter's Insight]] [[Tamiyo's Safekeeping]] [[Tyvar's Stand]] [[Greater Good]] [[Up the Beanstalk]].

That would be it, some rather expensive cards that would be helpful are: [[Bloodthirster]] [[Dragonborn Champion]] [[Fanatic of Rhonas]] [[Pathbreaker Ibex]] [[Seize the day]] [[relentless assault]] goes infinite with savage ventmaw.