The item that increases damage by 1.0 and grants a 1.5 times multiplier with Book of Belial in The Binding of Isaac is Blood of the Martyr; however, its effects do not stack with Magic Mushroom or Cricket's Head.
The item in The Binding of Isaac that provides a 1.0 Damage Up and grants a +50% / 1.5 times Damage Multiplier if paired with the Book of Belial, but does not stack with multipliers from Magic Mushroom or Cricket's Head, is A) Blood of the Martyr.
When combined with the Book of Belial, Blood of the Martyr not only gives a damage boost but also increases the effect of the book, making it a powerful combination in the game. However, it's important to note that the damage multipliers from Blood of the Martyr do not stack with those provided by Magic Mushroom or Cricket's Head, as these items have similar effects that do not stack with each other according to the game's mechanics.