Thank you everyone for the answers. The interaction between these two cards is legal. As some users noted, the ability of Boromir of sacrificing himself has two effects: making creature indestructible and The Ring Tempts You. The Ring Tempts You by itself makes the new ring bearer (that will be the new non-legendary zombie Boromir token) Legendary, which is part of the requirements for Ratadrabik’s ability. Thank you again everybody.
Thank you everyone for the answers. The interaction between these two cards is legal. As some users noted, the ability of Boromir of sacrificing himself has two effects: making creature indestructible and The Ring Tempts You. The Ring Tempts You by itself makes the new ring bearer (that will be the new non-legendary zombie Boromir token) Legendary, which is part of the requirements for Ratadrabik’s ability. Thank you again everybody.