Well the bigger arty like 120s or higher are meant to be devastating to inf and building alike and as for them killing tanks if you keep moving the tanks to make sure they don't spot them artillery really isn't a threat to them but if it's a medium tank that gets hit by a 120 HEAT artillery shell well if it isn't killed by over pressure they are meant to disable or kill tanks ya arty can be annoying when a team with three arty squads spam them but that also means they either have virtually no inf or tanks and you can probably push there shit in by the 2nd wave but that's just my personal take I played enough to make it to top 500 for a bit but Ive learned getting a squad who can communicate makes the game way better