The issue is that the probing is useless and achieves nothing if the Spear Guards are up. All it tells us is that he has Spear Guards, which we already know.
Our ranged attacks will also be defended against with the Spear Guards is the thing...we just can't meaningfully probe his defenses at all with those up.
That is admittedly an issue. I think that if we really made it appear like we were up for a long-ranged game of attrition, we might force him to try closing the distance with us and demonstrating some of his other abilities, but it's a gamble.
If we're using Devouring Blaze off the bat, then honestly I'd be tempted to go a little harder on the attack here, to capitalise on this being a turn when he's unaware that we have Devouring Blaze and give us the chance to sucker punch him. Punch up the dice on some of the Firebomb Strikes, maybe. Even for testing the waters, I think they may be on the lower end - Axe Man was throwing attacks at us with more dice than that.