Blue powder? I'm not sure. It could be explosive or poison. I can dismantle the trap I think. But I'd like you other guys more than 30 ft away when I do.

"Blue powder?" wonders the gnome out loud, "I bet it is the same stuff as in the vial.  So probably not explosive but I bet the evocation part is a gust or breeze to blow the dust in the face of the person opening the chest!" Reginald considers a moment, "I wonder if the powder is contact or breathed in? Either way, be careful Trem!""

Roxaria steps back further away from the chest after hearing Reginald’s hypothesis. “I don’t like this one bit. Could we put a bag or something over the hole and when we open it, the powder will blow into the bag, protecting us?”  She shrugs unsuredly.

    Kha glances around the cavern. "I don't think we have that kind of space here unless we get back on the other side of the water. I hope that frog is still here." He steps to the edge of the pool and attempts to call the large amphibian again.

(Animal handling, 18 with guidance)

     "I'll stay with you so I can give you Kord's blessing. It doesn't last long, so I we will need to wait until the others are at a safe distance to open the thing."

Trem gets out his Thieves Tools and waits for everyone to get ready.

(Guidance is a d4 right?)

The massive frog rises at Kha's call and waits at the edge of the lake

Guidance is a D4

Roxaria gets onto the frog. “Just be careful Kha and Trem.”

Don't worry! We got this! Right Kha?

      "Will do," Kha replies Roxaria with a confident smile. He then glances down at Trem as the rest depart. " Sure. And if it doesn't... Well, I guess we'll have some skin in the game then, huh?" 

     The cleric then touches Trem on the shoulder and calls upon Kord to aid the elf's eyes and hands in disabling the trap. 

Trem uses his Thieves Tools to disarm the trap: nat 1 (rolled in game log)

(Trem please roll a Constitution Save.)

Trem accidentally knocks some of the blue powder onto himself with his Thieves Tools as he tries to disarm the trap.

(Do the Thieves Tools break?)

Con save: 9 (rolled in game log)

Aaaahg!

Thieves Tool are still intact

Trem is now infected with the Frigid Woe. Symptoms will manifest in 2 days and your speed is reduced by 5

Get back with the others, Kha. It doesn't matter for me anymore...

(Is the chest (still) locked? And is speed reduced right now or when the symptoms manifest?)

(There is still time to find a cure. Every 10 days Trem rolls a con save. He only dies when his speed is reduced to 0)

Quote from Acjots >>

Aaaahg!

 Roxaria is startled to hear Trem’s scream echo through the cavern. “We need to go back! How do we turn this frog around?”

She kneels down and prods the giant frog with her hands trying to coax the frog back to Trem and Kha. “C’mon! Turn around!”

The chest was never locked, just laden with a trap.

Speed is reduced when the symptoms manifest in 2 days. For now your the same as usual, but in 2 days you will see blue veins sprouting across Trem's body

(Reminder that Trem does know a part of prayer for Tiamat)

The massive frog turns around and once again lets the party off of his back when it reaches the lake edge.

Roxaria jumps off the frog and rushes up to Kha and Trem, “What happened?  Is anyone hurt?”

Just my pride... I got some of that blue stuff on me. So I might as wel open it. Go back and take Kha with you, I'll open the chest. I remember a little bit of a prayer, maybe it's enough. Maybe not, but I don't think it matters anymore...

“I managed to somehow turn that giant frog around. I’m not sure if I can do that again though.  Can we just sit back at the entrance that way if you need to make a hasty escape, you can just run and jump on the frog also?”