I want to prevent my border routers from responding to pings and traceroutes from outside addresses yet pass ICMP packets if I'm pinging from my internal addresses.
If I apply this ACL to my interface will it do what I need:
access-list 120 deny icmp any host 18.104.22.168 echo
The access-list is applied inbound to the outside interface so it will stop any echo requests from outside coming in.
But if you initiate a ping from inside the network then the packet that comes back inbound to the outside interface is not an echo request but an echo reply and you are not blocking echo replies with this access-list.
So in short, yes it will allow you to ping out :)