There's other two that can deal huge damage to towers.

Most importantly, Gildur, he only needs S1 to charge his 4th attack and doesn't lose that much health, if he does at all, because of the shielding the skill gives him. Dunno if the S1 damage is a build specific thing but i haven't checked the meta items.

There's also Vahein with purely autoattacks, but he loses a lot of health while soloing towers if there's no minions, unlike Gildur. Again doubt if meta but i couldn't even test the actual build yet (no jungle items in training, had to replace it with a less powerful similar item, also, everyone picks the role and i have to find it before picking it.

Anyway, the build is something that can only be exploited on Val as far as i know, i tried doing the same on other marksmans with high at but it only works on Valhein).