Technology 2 will prevent him from firing normal tears, even tear-changing effects like Brimstone.
Technology 2 will no longer prevent him from firing normal tears and instead will cause him to also fire Technology lasers out of his right eye instead of his normal tears. These Technology shots have the same synergies and interactions with other items on top of the Technology 2 laser. Neptunus lets him fire tears normally. These lasers cannot be angled with momentum.
Strategy
Cain starts with slightly higher damage and speed than most characters, making him more agile and effective at the start. However, he has lower range and health than average, which means he has to put himself closer to danger and can take less punishment than most.
As mentioned above, Cain only shoots tears from his right eye. This makes it easier to aim as him, and lets Cain consistently peek around corners to shoot behind cover.
Cain's kit makes him the best character for hoarding items. His starting luck increases the chance of a drop after a room clear, and Lucky Foot boosts this even further by increasing his success for room drops and machines like Slot Machines, Fortune Telling Machines, Shell Games, etc.
If Paper Clip is unlocked, Cain can unlock every golden chest he finds, which significantly increases the chance for an item or a mass collection of pickups.
Cain's luck makes him a good candidate for tear effects, as many of them are more likely to trigger based on luck.
As he starts with only two hearts, Cain benefits from early health ups, and is not a very good candidate for Devil Rooms early on since they will significantly cut his endurance.
As Cain is likely to have a large collection of coins or keys after a few floors, it is wise to open up Shops, bomb Shopkeepers, donate ten coins to a Donation Machine, or donate to a Beggar till he pays out to maximize the chances of an Angel Room. Cain benefits more from them compared to Devil Rooms due to his low health.
Because Lucky Foot changes bad pills into good pills, pills are extremely effective for Cain. This makes Golden Pills and Echo Chamber great finds for Cain, as he will receive multiple guaranteed buffs from the pills.
Item Interactions
Abel's tears become red and deal 7.5 damage when held by Cain.
Birthright: Grants +1 luck. All floors that can have special rooms contain an upgraded Arcade.