15 Most Useful X words:

AX(E): a tool for cutting, such as cutting trees
EX: a former romantic partner
XI: a Greek letter
OX: an animal known for hauling a large load
XU: a former Vietnamese coin
OXO: containing oxygen
TIX: tickets
GOX: gaseous oxygen
XED: expurgated
VAX: vaccination
VOX: voice
ZAX: a tool used primarily for roofing
OXY: containing oxygen
REX: king
COX: to navigate a boat

Other useful X words:

EAUX PIXIE NIXIE NIXY EXUVIA(E)
AXIAL AXION IXORA DOUX ROUX
JEUX COXA(E) IBEX ONYX MINX
LYNX EXEC IXIA LUXE (S)ILEX
OXID(E) OXIC OXER FOLX MPOX
MIXT FIXT PREX(Y) ADDAX XENIA

AXAL AXED AXEL AXIL AXON BOXY BRUX CALX COXA CRUX DEXY DOUX DOXY EAUX EXEC EXED EXON EXPO FALX FAUX FIXT FLAX IBEX ILEX IXIA JEUX LUXE LYNX MAXI MINX MIXT MOXA NIXE NIXY ONYX ORYX OXER OXIC OXID OXIM PIXY PLEX PREX POXY ROUX SEXT TAXA VEXT XYST

ADDAX ADMIX AFFIX ATAXY AUXIN AXIAL AXILE AXILS AXING AXIOM AXION AXITE AXLED AXMAN AXMEN AXONE BEAUX BEMIX BORAX BOXLA BRAXY BUXOM CALIX CALYX CAREX CIMEX CODEX COMIX COXAE COXAL COXED COXES CULEX CYLIX DEOXY DESEX DEWAX DEXES DEXIE DIXIT DOXIE EPOXY EXALT EXINE EXING EXPAT EXTOL EXUDE EXULT EXURB FAXED FEDEX FIXER FIXIT FLAXY FOREX FOXED GALAX GOXES HAPAX HEXAD HEXER HEXYL HYRAX IMMIX INBOX INFIX IXNAY IXORA IXTLE KEXES KYLIX LATEX LAXER LAXES LAXLY LEXES LEXIS LOXED LUREX LUXER MAXED MAXIM MIREX MIXUP MOXAS MUREX MUXED MUXES NEXTS NEXUS NIXIE OXBOW OXEYE OXIDE OXIME OXLIP OXTER PAXES PHLOX PIXES PIXIE POXED PREXY PROXY PYREX PYXES PYXIE PYXIS RADIX RAXED REDOX REDUX REFIX REMEX REMIX RETAX REWAX REXES SEXER SEXTO SILEX SIXER SIXMO SIXTE TAXER TAXOL TAXON TAXUS TELEX TEXAS TWIXT UNBOX UNFIX UNMIX UNSEX VARIX VEXER VEXIL VOXEL WAXEN WAXER XEBEC XENIA XENIC XENON XERIC XEROX XERUS XYLAN XYLEM XYLOL XYLYL XYSTI

Useful X bingos:

ALEXINE ANOREXIA DIOXANE EUTAXIES EXERTION
EXONUMIA EXPIATOR GEOTAXIS OXIDATE RELAXIN
SAXATILE SILOXANE VEXATION TOXEMIA ATAXIES
DEXTRIN DEXTRAN EXORDIA EXOTICA OXALATE
OXIDANT REXINES TOXINES XENOLITH RADIXES