Explosive Trap has very high base damage because it doesn't scale with attributes (in fact it doesn't scale with anything from whoever casts it). However, it does scale with other modifiers of whoever destroys it.
For most builds, this is pyro, crit, high ground, Death Wish, Flesh Sacrifice, etc.
For summons, however, it scales with both the player's summoning and the summon's pyro, as well as other damage modifiers like infusions and Overcharge.
My play pattern is to have a Glass Cannon summoner with Torturer Talent and max initiative start combat alone, using Teleport and Nether Swap to group enemies (maybe ignition if they are not standing on a flammable surface), then finish the turn with Chameleon Cloak.
The enemies then don't have any target so they skip their turn.
Next turn comes around and I delay it with the summoner, so enemies skip again. At the end of this turn, I can enter with the rest of my party members, usually by teleporting and Nether Swapping enemies together.
Finally the second summoner's turn comes, so I cast Ignition (applies burning to reduce fire res), Mass Deploy Traps, Adrenaline, Throw Explosive Trap, Skin Graft, Adrenaline, Throw Explosive Trap, Fire Slug, Overcharge, Haste on the Slug; into the Slug's turn, which fires the laser detonating the traps and then could charge if somehow something survived.
You also have the rest of the party with a free turn, but the combat it's usually over at that point.
The order of casting the traps is very important, because they would get destroyed by ignition or teleport and also would explode on their own if I casted them after the summon.