There's a couple of ways you can reach Lord Incendius, both ways are as difficult however the 2nd guide is recommended for a solid party since the mobs are more higher level:

1a) Go up to the Ring of Law and defeat the boss there, then exit to the west into the room with the dwarfs and fire elementals.
1b) Go up the next ramp behind you right next to the ramp you've come up from the Ring of Law to where the neutral spectators are (do not fight them) and go to the other side of the room.
1c) Fight the hostile humanoids you see down the ramp, then work your way up north over the bridge fighting through a couple of dwarfs and elementals into the room with more humanoids and bloodhounds.
1d) Work your way down out of the small maze of rooms to an upper semi-circular area with more groups of humanoids you'll need to battle through at the entrance.
1e) Drop down to the level below you where you'll need to fight a couple of elementals before proceeding engaging Lord Incendius in the middle of the circular room to the north-east.

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2a) Use the Shadowforge Key to open the gate at the left of the instance entrance, defeat the elemental, and proceed to the area with the long path that's lined with dwarf, bloodhound, and elemental patrols - fight them as necessary.
2b) Proceed east into the next area where there's groups of dwarfs that patrol back and forth - fight them to get to the opening in the wall ahead of you to the north-east with another group of dwarfs hiding behind it which you'll need to defeat.
2c) Continue up the path north-east fighting all the elementals until you reach the circular room with Lord Incendius.

to get this quest you need to complete teh quest which is the only one available, the one involing Overmaster pyron.

After you kill him and turn in the quest he gives you this one.

where can i get this quest?

where is the lord at?

k, so i know where Incedious is, but where is the tablet?