Way of Jotun

Monks who follow the Way of Jotun (jötnar in Old Norse, a cognate with ettin) revere the power and grandeur of Giants. They alter their own bodies to resonate with giants might, channeling it to augment their prowess in battle, grow to large or huge size, and eventually become a Giant. As a follower of this Monastic Tradition, you decide how you unlocked the power of Giants.

Giant Might

Starting at 3rd Level, you can imbue yourself with the might of giants. As a bonus action, you magically gain the following benefits, which last for a number of hours equal to half your level rounded down: 

• You become Large (your Martial Arts Die increases by one size), along with anything you are wearing. If you lack the room to become Large, your size doesn't change.
• You gain temporary hit points equal to 2 times your monk level. These temporary hit points last until you take your next long rest.
• Your monk weapon attacks and unarmed strikes deal an extra 1d4 damage.

You can use this feature twice, and you regain all expended uses of it when you finish a long rest.

Great Stature

At 6th Level, you grow a number of inches in height equal to roll 3d6.  Moreover,  when you use your Giants Might feature, you can choose to grow to a huge size(Martial Arts Die goes up by two sizes) and gain 3 times your monk level in temporary hit points, and the extra damage you deal with your Giant Might feature increases to 1d6 while you are a huge size.

Giant Mastery

Starting at 11th level, you can choose to expend two uses of Giants Might to take the form of a monster of type Giant whose challenge rating is equal to or less than your level. This form lasts a number of hours equal to half your level rounded up. 

• Your game statistics are replaced by the statistics of the Giant, but you retain your alignment and personality. You also retain all of your skill and saving throw proficiencies, in addition to gaining those of the creature. If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature’s bonus instead of yours. If the creature has any legendary or lair actions, you can’t use them.
• When you transform, you assume the beast’s hit points and Hit Dice. When you revert to your normal form, you return to the number of hit points you had before you transformed. However, if you revert as a result of dropping to 0 hit points, any excess damage carries over to your normal form. For example, if you take 10 damage in Giant form and have only 1 hit point left, you revert and take 9 damage. As long as the excess damage doesn’t reduce your normal form to 0 hit points, you aren’t knocked unconscious.
• Your ability to cast spells, and your ability to speak or take any action that requires hands is limited to the capabilities of your Giant form. Transforming doesn’t break your concentration on a spell you’ve already cast, however, or prevent you from taking actions that are part of a spell, such as haste, that you’ve already cast.
• You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can’t use any of your special senses, such as darkvision, unless your new form also has that sense.
• You choose whether your equipment falls to the ground in your space, merges into your new form, or is worn by it. Worn equipment functions as normal, but the DM decides whether it is practical for the new form to wear a piece of equipment, based on the creature’s shape and size. Your equipment does change size or shape to match the new form, and any equipment that the new form can’t wear must either fall to the ground or merge with it. Equipment that merges with the form has no effect until you leave the form.

Blessing of the All Father

At 17th level, you can use your Giants Might, Great Stature and Giants Mastery an unlimited number of times.

In addition, you can utilize your Giant's form Legendary actions, 1 legendary resistance that refreshes on a short rest and if you are in your home the Giants Lair actions as well.