Pingers are creatures or permanents that repeatedly deal small amounts of direct damage, traditionally one damage at a time. The nickname comes from turning tiny increments of damage (pings) into removal, combat manipulation, or eventual wins.
Giving a pinger deathtouch through Basilisk Collar can turn every point into lethal creature damage. Torbran, Thane of Red Fell and Ojer Axonil, Deepest Might instead make red pingers considerably more painful by increasing their damage.