CREATE TABLE table_21256068_3 (opponent VARCHAR, venue VARCHAR, competition VARCHAR)

state the opponent on halliwell jones stadium in super league xiv
SELECT opponent FROM table_21256068_3 WHERE venue = "Halliwell Jones Stadium" AND competition = "Super League XIV"
SELECT "opponent" FROM "table_21256068_3" WHERE "Halliwell Jones Stadium" = "venue" AND "Super League XIV" = "competition"