Herald of Bolas

When Herald of Bolas enters the battlefield, if {u}{b} was spent to cast it, target player sacrifices a creature, then draws a card; if {b}{r} was spent to, it gains "If a player would gain life, they lose that much life instead"; if {u}{r} was spent, it gains "The first instant or sorcery you cast each turn costs {2} less to cast". (Do all three if {u}{b}{r} was spent)