pantheon is a very strong character, who can stun and damage multiple champions at the same time,
his damage bonus is massive on his q and e abilities and most people dont see that. This build is full ADC and trust me, vs the right enemy´s you will dominate them. Pantheon can be a good hybrid between tank and AD to, but his build isn´t ment for that. if the enemy´s build much armor at the beginning you should get last whisperer earlier.