Interesting wording on Hidden Step, though. It makes you invisible "...until you attack, make a damage roll, or force someone to make a saving throw." This is different from all other invisibility effects. I wonder why.
Most other forms of invisibility are broken if you attack or cast a spell, so the different phrasing in this case isn't creating a different result when casting sacred flame.The main reason I see is that this wording includes the non-targetting attack cantrips that are in the cleric's and druid's repertoire. So "Sacred Flame" (e.g.) would also take out the invisibility from Hidden step.
Most other forms of invisibility are broken if you attack or cast a spell, so the different phrasing in this case isn't creating a different result when casting sacred flame.
It is different because invisibility normally breaks if the invisible creature casts a spell that doesn't have anything to do with anyone else, such as mage armor or false life, or that is entire beneficial like cure wounds - but the firbolg's invisibility from this racial feature would stay in place through casting all of these spells.
Choose:Why put in a race that diverges so significantly from the original other than to pander to nostalgia? Why not create new races or utilise the plethora of other available options if they want to fill a book?
Firbolg have been 10 ft. tall since 1e and in every other edition. They've always been of a large size and, in fact, one of their special abilities has always been to shrink down a size. It's really just absurd to shoehorn them into a medium build so that they'll be a playable race.
I can't speak for "all other" effects, but the Invisibility spell ends when you attack or cast a spell.Interesting wording on Hidden Step, though. It makes you invisible "...until you attack, make a damage roll, or force someone to make a saving throw." This is different from all other invisibility effects. I wonder why.
Off the top of my head I can think of two things.There's currently no explicit bonus to being large
I'll give all the sceptics this:It helps that the Firbolg was given a unique identity beyond "Tall human," even if it did divert from the original lore, while the Goliath was stuck for the most part with the "Tall competitive people."
I had to go back and check the changling and I have to say, the Firbolg is not better than them at disguise. For the changeling, it is a physical change; the firbolg's is an illusion and can be seen through with an intelligence/investigation check. It also only lasts an hour and requires the firbolg to have at least a short rest to recharge it. The changling is a physical change, so it can't be seen through. It is an at will action to change, they do not have to rest to recharge, and it lasts essentially forever. They also have proficiency in deception as a racial ability.
A changeling is far superior at disguise than a firbolg for anything long term or with preparation and I would prefer a changeling as an infiltrator.
The firbolg's disguise self is useful only in that it can also change the appearance of their clothes with their new disguise. However, they are unable to change their appearance again during the duration of the spell.
Off the top of my head I can think of two things.
Large weapons (significant damage increase*) and ability to grapple huge creatures (significantly reducing the number of grapple-immune foes).
*) I can't actually find a rule that governs how damage changes with the size of weapons. There's nothing in the Equipment chapter of the PHB. The MM talks about how size changes your hit dice, but not your weapon dice. The DMG does say you double the damage dice for a weapon wielded by a Large creature, but it is far from obvious this should apply to player characters. After all, the Enlarge spell makes PCs Large but only allows +1d4 damage.
And on the downside (just as you say), the inability to follow the rest of the party through cramped environments. (Of course this is not a big deal if you have an ability to shrink, or if your DM allows access to those Underdark fungus detailed in Out of the Abyss). I guess another downside (at least for the first few levels) is that you can't actually block goblins and other small creatures.