This is most important time of pantheons life, you win early you won the game, you lose early well..good luck tanking later and picking enemies 1 by 1 somehow.
Playstyle should be max poke Q on short range so it loads quicker and you are looking for that lvl 2 while conqueror is stacking bcs you have short spear cd so you can stack whole conq just with spear. After you stack it jump on enemy preferably with epowered W and Q him hard or wait 2 basic depends on his mobility
Land ranged spear shots only when there are clear shots with no minion in between in early

In mid game you should be having black cleaver and death dance so you are tanky and strong enough
Engages with enpowered W are favoured because you get 3 stacks of enpower and can quickly stack next ability
If you are about to tank alot enpower E and watch your steps so you dont get backstabed by Bulgarians. Q is great especially on conqueror and enpower bcs it heals you alot especially if you hit more then 1 champ, throw it only if you must preferably just melee

Watch for fights in late game especially baity ones that start 4v5 so you can good ult
For ult you need to predict and you can either use it to engage in enemy or in middle of the fight to catch them up or dipp for few sec so they switch focus
Ult does fairly decent dmg

You can combo tb and ult so you back up go towards mid or bot and ult them or where the fight is and then after fight tp top
you can also go mid from top but you need good aim and dumb enemy to land that

Try your best to land spear shots on runing enemies or enemies in mid fight dying below 25% so you can execute them and potentionaly steal kill

I hope you enjoyed iron guide pant
For fatherland protecting bonus you have to buy DLC expansion and battlepass irl to read that part
Hope i did not waste much of your time now go and get that gold