Bard

Dual-classing

Bards are an exception to the regular dualclassing rules. A character intending to become a bard need not meet the standard ability score requirements for dual-classing, merely the requirements for the bard class. Furthermore, the character is able to switch from thief to bard even before surpassing their fighter level, if desired.

Other than this, the fighter/thief dual-class follows the standard dual-classing rules.

Half-elves

Only when a half-elf intends to become a bard can that race dual-class, and only into classes required for achieving bardhood. This is a special exception.

Abandoning the goal of bardhood

If a dual-classed character abandons plans to become a bard, or if they become ineligible due to surpassed prerequisite level limits, the player must select “fighter”, “thief”, or “fighter/thief” as the character’s class. The latter option is available only to half-elves (as a multi-class), or to humans who meet the standard ability score requirements for non-bard dual-classing. If the fighter or thief class is lost, so too is XP accumulated for that class.

Hit dice

Hit dice rules for the fighter and thief hit dice are the same as those rules for standard dual-classing. However, six-sided hit dice gained from Bards Table I on PHB 117 do NOT function the same as the standard dual-classing rules – they are actually in addition to whatever was gained from the fighter/thief dual-class.1) PHB 118, “All bard hit dice (and additional hit points) are additions to existing hit dice — none are lost for becoming a bard.”.

Abilities as a bard

Once the character has become a 1st level bard, unlike with normal dual-classing, the previously-attained abilities of the fighter and the thief classes are instantly obtained.2) PHB 118, “A bard always engages in combat at the level he or she attained as a fighter. A bard is able to function as a thief of the level previously attained.”

Note that the bard has access to the druid's saving throw table as though the bard was a druid of the same level as the bard level, and can make use of those saves if they are better than the fighter and thief saves to which the bard has access.3) PHB 118, “All saving throws are made on the most favorable table, with the actual bard level considered as that of a druid.”

Bards do not obtain the abilities of a druid other than those listed in the bard rules (e.g. saving throws). The character is effectively a fighter/thief/bard, not a fighter/thief/druid/bard.

Instruments

The bard can choose whatever instrument is desired to be their instrument of focus,Ex but it must be stringed.4) PHB 118, “He or she must always have a stringed instrument.”. DMs: It's also important that the instrument has strings so that it is susceptible to saving throws for things as flimsy as instrument strings.