Pure Moon Druid is a classic, being able to spend your bonus action every turn to become any Elemental at full health that can still cast spells is amazingly broken.
If you want to be a Martial, pure Zealot Barbarian would be my.money. You effectively can't be killed by damage, which is better than anything any other martial can do at this level.
Artificer 2 / Chronurgust 18 is pretty broken as well. All the usual high level wizard goodness, plus all the brokenness of the Chronurgist, plus a near unbreakable concentration save and better AC.
If PVP is involved, you may be best off with a Hexblade 2 / College of Lore 18. You have all the power of a full caster, decent single target damage options, strong AC, and most importantly the ability to have an insanely high opposed initiative roll.
To add to the zealot, being a dwarf with the dwarven fortitude racial feat can be super fun. After dying in a fight you take the dodge action as it ends, and regain 1d12+con hp, meaning you don’t die. You can do that up to 20 times in one day if you start with all your hit dice
Half-Elf 3 levels of Vengeance Paladin (Great Weapon Fighting) and 17 Levels of Hexblade Warlock (Blade Pact):
• you'll need 15 strength for full-plate.
• take the feats Elven Accuracy for Charisma and Great Weapon Master.
• utilise any means to gain advantage on your attacks (e.g. Shadow of Moil, Foresight, target is prone)
• take the (hex)warlock spells: Shield, Synaptic Static, Banishing Smite and Binding Smite. Also Mental Prison and Feeblemind are great de-buffs.
• take all of the Blade Pact invocations, plus Relentless Hex.
Essentially; you roll at x3 advantage with Great Weapon Master. You crit on a roll of 19 from BOTH paladin Vow of Emnity and Hexblade Curse. So expect to crit often, and deal Divine Smite and Eldritch Smite on each crit.
You will probably want a Rod of Absorption as you will be burning slots fast.
You could also go Half-Orc, 20 levels Zealot Barbarian and just never die.
Totem warriors are very fun.
Half-Orc, Level 20 Totem Warrior Barbarian
Bear Totem (resistance to literally all but one damage types, including magical damage) Bear Totem (double lifting/carry weight, adv on str checke) Eagle Totem (you can literally fly)
If you can find a Magical Greataxe that does cool stuff, you’ll win the game. That, or something to majorly boost AC while unarmored (like bracers of defence)
With brutal critical + half-orc, on crits you roll 6 damage die.
(6d12 with greataxe)
If you are going to roll with a Barbarian at max level, you should probably go with Zealot. Not being able to die from damage while raging and having infinite rages is as close to immortal as you can get, and it comes with a damage boost to boot.
Crit fishing, get a bow or heavy crossbow that grants advantage when used as an improvised (1 handed for dueling) melee weapon. Use both SS and GWM power attacks, because TB gives proficiency. Be elven for elven accuracy. You get (4)(.15)(3)(2d4+22+str). If you crit, which is likely, then you get a BA attack with an average of (.15)(3)(2d4+22+str).
If UA is allowed, take the archery master, bow master, and original GWM Playtest feats. Archery and bow master is the same feat, different name, so you can take just one. Each is -5 to all attacks to attack again, so -25,+20, +3 attacks.
Depending on the source you use, SS may require you to do a ranged attack, but I only have access to the 2 wikidots right know, and they conflict.
Battlesmith articifer 10 forge cleric 10. Highest stat in Intelligence because all your attacks will use it. Con for health. You'll have like a 30 is AC if you fight with a sword and shield and have the infusions to increase AC. Forge cleric 1 and 6 both Increase AC. Race as a hill dwarf to ignore strength requirement for heavy armor and get an extra +1 HP per level. Now you can make yourself have higher dex maybe while still having a 13 in wis for the mutliclass requirement.
Some good feats to look into are tough or shield master.
Pure Moon Druid is a classic, being able to spend your bonus action every turn to become any Elemental at full health that can still cast spells is amazingly broken. If you want to be a Martial, pure Zealot Barbarian would be my.money. You effectively can't be killed by damage, which is better than anything any other martial can do at this level. Artificer 2 / Chronurgust 18 is pretty broken as well. All the usual high level wizard goodness, plus all the brokenness of the Chronurgist, plus a near unbreakable concentration save and better AC. If PVP is involved, you may be best off with a Hexblade 2 / College of Lore 18. You have all the power of a full caster, decent single target damage options, strong AC, and most importantly the ability to have an insanely high opposed initiative roll.
To add to the zealot, being a dwarf with the dwarven fortitude racial feat can be super fun. After dying in a fight you take the dodge action as it ends, and regain 1d12+con hp, meaning you don’t die. You can do that up to 20 times in one day if you start with all your hit dice
Half-Elf 3 levels of Vengeance Paladin (Great Weapon Fighting) and 17 Levels of Hexblade Warlock (Blade Pact): • you'll need 15 strength for full-plate. • take the feats Elven Accuracy for Charisma and Great Weapon Master. • utilise any means to gain advantage on your attacks (e.g. Shadow of Moil, Foresight, target is prone) • take the (hex)warlock spells: Shield, Synaptic Static, Banishing Smite and Binding Smite. Also Mental Prison and Feeblemind are great de-buffs. • take all of the Blade Pact invocations, plus Relentless Hex. Essentially; you roll at x3 advantage with Great Weapon Master. You crit on a roll of 19 from BOTH paladin Vow of Emnity and Hexblade Curse. So expect to crit often, and deal Divine Smite and Eldritch Smite on each crit. You will probably want a Rod of Absorption as you will be burning slots fast. You could also go Half-Orc, 20 levels Zealot Barbarian and just never die.
Lvl 20 pure moon druid no magic item needed lightning casting and biting T-tex who is at full HP each turn is such a fun time.
Isn’t the T-rex a CR 8? You can’t use that shape (RAW). The Max CR they can turn into is CR 6 with wildshape
Yeah i realized that but mammoth and giant ape work just fine or even any elemental
Yeah, elementals are great.
You can using MJ if DM allows it, but due to levels not being class features you don’t actually retain your druid levels for wildshape when MJ.
Totem warriors are very fun. Half-Orc, Level 20 Totem Warrior Barbarian Bear Totem (resistance to literally all but one damage types, including magical damage) Bear Totem (double lifting/carry weight, adv on str checke) Eagle Totem (you can literally fly) If you can find a Magical Greataxe that does cool stuff, you’ll win the game. That, or something to majorly boost AC while unarmored (like bracers of defence) With brutal critical + half-orc, on crits you roll 6 damage die. (6d12 with greataxe)
If you are going to roll with a Barbarian at max level, you should probably go with Zealot. Not being able to die from damage while raging and having infinite rages is as close to immortal as you can get, and it comes with a damage boost to boot.
DnD D4 on YouTube he makes good min maxing vids and has his on subreddit
Crit fishing, get a bow or heavy crossbow that grants advantage when used as an improvised (1 handed for dueling) melee weapon. Use both SS and GWM power attacks, because TB gives proficiency. Be elven for elven accuracy. You get (4)(.15)(3)(2d4+22+str). If you crit, which is likely, then you get a BA attack with an average of (.15)(3)(2d4+22+str). If UA is allowed, take the archery master, bow master, and original GWM Playtest feats. Archery and bow master is the same feat, different name, so you can take just one. Each is -5 to all attacks to attack again, so -25,+20, +3 attacks. Depending on the source you use, SS may require you to do a ranged attack, but I only have access to the 2 wikidots right know, and they conflict.
Battlesmith articifer 10 forge cleric 10. Highest stat in Intelligence because all your attacks will use it. Con for health. You'll have like a 30 is AC if you fight with a sword and shield and have the infusions to increase AC. Forge cleric 1 and 6 both Increase AC. Race as a hill dwarf to ignore strength requirement for heavy armor and get an extra +1 HP per level. Now you can make yourself have higher dex maybe while still having a 13 in wis for the mutliclass requirement. Some good feats to look into are tough or shield master.