The Bomb: Wow, this took me long to figure out. Here's what I did: Put ALL available points into speed (Respec if necessary), put equipment on that boosts your speed and bring the following abilites: Withdrawal (max), Agile Exposure (max), Shadow Blend (max), Toxicant Form, Leading Strike. Use this sequence to inflict damage: Corrosion - Toxicant Form - Shadow Blend - Agile Exposure - Withdrawal. My Bio inflicts about 29,000 damage (31k) with that combo (!), depending on your stats it might be more if you have good equipment. Mine was average because I threw away some high speed-bonus stuff. Fill in with Agile Exposure and Leading Strike, then repeat the whole sequence (7 turns per cycle due to the cooldown of withdrawal) until finished. Your teammates will also benefit from the Agile Exposure and Corrosion, making them inflict more than double damage.
I read this to beat the time bomb. But When I did a "withdrawal combo",my damage was 1900 instead of 29000.