This applies when you are fighting ANY champion, use Khan's ability where he can pick up enemies to throw them off the map, this is very useful if the map has many ledges you can chuck enemies off.

Talus is a good champion to flank Dredge. Talus can disrupt Dredges flow of dealing damage and stop him from spamming his AoE (Area of Effect) attacks. Talus should kill him if he can but teleporting back to his portal is still ok as you dealt damage

Ruckus can activate a shield, if you are finding it hard to kill him then purchase "wrecker" from the item shop, getting it to tier 3 shreds through his shield.

Dredge may have good long range damage but he is very bad at dealing with flanks up close. It's best if he doesn't see you flanking him so a champion such as Skye is best.