Thrace is a bit far for TO .
Defend against Denmark. One winning war should be enough to make them relenquish their core.
Annex Pommerania when the Emperor is busy elsewhere (France/Hungary/Austra are great distractions for Bohemia)
Avoid War with Poland/Lithuenia unless the GH is trampling them hard.
If all else fails invade Russia. An alliance with Muscow will crush Novgorod. Release Finland as a buffer against Sweden and encircle and annex Novgorod capital for a Juicy COT.
Defend against Denmark. One winning war should be enough to make them relenquish their core.
Annex Pommerania when the Emperor is busy elsewhere (France/Hungary/Austra are great distractions for Bohemia)
Avoid War with Poland/Lithuenia unless the GH is trampling them hard.
If all else fails invade Russia. An alliance with Muscow will crush Novgorod. Release Finland as a buffer against Sweden and encircle and annex Novgorod capital for a Juicy COT.