Delayed Explosion - "You hear a click..."
A trap that causes a highly-damaging explosion a few turns after triggering: Enough time to rush/phase door/blinding speed away, but not enough to run normally.
Water Trap - "Sheets of water crash from the ceiling!"
Turns the trap (and the floor tiles surrounding it) into water tiles.
Alarm Trap (V2) - "The floor beneath you glows red..."
Summons some beasties from both staircases, which immediately path towards you.
Lethargy Trap - "You feel strangely lethargic."
Activates the cooldown on 1-4 of your skills.
And here's a few I'm less serious about
Boss Trap - "You hear a low chuckling/wheezing shriek/aggravated grunt..."
Only appears on levels with bosses. Alerts said boss to your presence.
Blood Of Life Trap - "Your blood runs cold."
Only generates if you've drunk the Blood of Life. Gives you a status effect that renders it ineffective for some turns.
Level-Wide Trap - "You hear a menacing hum. Better run - now!"
Starts a countdown for you to get off the current level. Remaining on the level at the end of the countdown deals you massive arcane damage.