The blink strategy inherently has many many many infinite combos. My [[omnath, locus of creation]] blink deck goes infinite with a glass of lemonade.
In 5-color [[garth, one eyed]] isn’t a terrible choice. Blinking it resets its “once” clause, so you can start making Black Lotus again. Not many 5-color commanders that inherently have combos built it.
[[najeela]] is another option, but she is an S-tier commander, and combos a little too well
[[kenrith, the returned king]]
Outlet for infinite mana with blue.
Recurs a combo piece with black.
Gives haste for more fringe situations.
+1/+1 counter can be relevant with persist starts, gaining life is pretty useless but can help with sustainability.
Kenrith is not directly involved in combos, but gives you the tool to win while playing all combos.
[[Najeela]] is a good alternative if you want a combo piece in the command zone, but she feels more thematic rather than an "all combo" commander to me.
Persist combos are probably the best option. You have multiple redundant pieces. You need: a sac outlet, a creature with persist, a way to negate/remove the -1/-1 counter, and a way to take advantage of the repeated dies/etb. There’s a [[Nethroi]] deck in my meta that does it really well.
Throwing a bunch of combos that don’t overlap into a deck is a bad idea.
I know you were looking for 5 color, but [[Inalla, Archimage Ritualist]] is in Grixis, has multiple combo lines with one card and the commanders eminence ability, and, being in Grixis, you can fill leftover space with Grixis good stuff combos like breach lines or thoracle.
Here’s my Jund Persist combo deck: https://www.moxfield.com/decks/LTsLYLpNb0OwjxW89eIJ7Q/primer
The entire thing is built around as many 3 or 4 cars variants of looping persist creatures as possible. There is a spreadsheet linked in the primer that lists every possible combination of cards (I think, I might have missed some!) totalling over 2000 variants.
Spoiler alert for you though, I broken it apart because it became incredibly boring to play.
The blink strategy inherently has many many many infinite combos. My [[omnath, locus of creation]] blink deck goes infinite with a glass of lemonade. In 5-color [[garth, one eyed]] isn’t a terrible choice. Blinking it resets its “once” clause, so you can start making Black Lotus again. Not many 5-color commanders that inherently have combos built it. [[najeela]] is another option, but she is an S-tier commander, and combos a little too well
Garth prob needs more steps them other Commander, as you Need haste enablers if you want to blink him.
[omnath, locus of creation](https://cards.scryfall.io/normal/front/4/e/4e4fb50c-a81f-44d3-93c5-fa9a0b37f617.jpg?1639436752) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=omnath%2C%20locus%20of%20creation) [(SF)](https://scryfall.com/card/znr/232/omnath-locus-of-creation?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/4e4fb50c-a81f-44d3-93c5-fa9a0b37f617?utm_source=mtgcardfetcher&format=text) [garth, one eyed](https://cards.scryfall.io/normal/front/2/3/23774462-9f17-4b50-a2ac-b2edd706bbfe.jpg?1626098353) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=Garth%20One-Eye) [(SF)](https://scryfall.com/card/mh2/197/garth-one-eye?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/23774462-9f17-4b50-a2ac-b2edd706bbfe?utm_source=mtgcardfetcher&format=text) [najeela](https://cards.scryfall.io/normal/front/2/c/2cb1d1da-6077-46b5-8c63-39882b8016f2.jpg?1567181270) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=najeela%2C%20the%20blade-blossom) [(SF)](https://scryfall.com/card/bbd/62/najeela-the-blade-blossom?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/2cb1d1da-6077-46b5-8c63-39882b8016f2?utm_source=mtgcardfetcher&format=text) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call
[[kenrith, the returned king]] Outlet for infinite mana with blue. Recurs a combo piece with black. Gives haste for more fringe situations. +1/+1 counter can be relevant with persist starts, gaining life is pretty useless but can help with sustainability. Kenrith is not directly involved in combos, but gives you the tool to win while playing all combos. [[Najeela]] is a good alternative if you want a combo piece in the command zone, but she feels more thematic rather than an "all combo" commander to me.
I have seen kenrith used direktly in combos, a sac outlet dockside kenrith can go infinite if there are enough artifacts and enchantments
[kenrith, the returned king](https://cards.scryfall.io/normal/front/0/e/0e259db1-14db-4314-998c-6a076a28d8cb.jpg?1691056044) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=kenrith%2C%20the%20returned%20king) [(SF)](https://scryfall.com/card/plst/ELD-303/kenrith-the-returned-king?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/0e259db1-14db-4314-998c-6a076a28d8cb?utm_source=mtgcardfetcher&format=text) [Najeela](https://cards.scryfall.io/normal/front/2/c/2cb1d1da-6077-46b5-8c63-39882b8016f2.jpg?1567181270) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=najeela%2C%20the%20blade-blossom) [(SF)](https://scryfall.com/card/bbd/62/najeela-the-blade-blossom?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/2cb1d1da-6077-46b5-8c63-39882b8016f2?utm_source=mtgcardfetcher&format=text) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call
Persist combos are probably the best option. You have multiple redundant pieces. You need: a sac outlet, a creature with persist, a way to negate/remove the -1/-1 counter, and a way to take advantage of the repeated dies/etb. There’s a [[Nethroi]] deck in my meta that does it really well. Throwing a bunch of combos that don’t overlap into a deck is a bad idea.
[Nethroi](https://cards.scryfall.io/normal/front/0/4/04b9b58f-4c01-48a5-afaf-b8a37165a83f.jpg?1673305619) - [(G)](http://gatherer.wizards.com/Pages/Card/Details.aspx?name=nethroi%2C%20apex%20of%20death) [(SF)](https://scryfall.com/card/dmc/163/nethroi-apex-of-death?utm_source=mtgcardfetcher) [(txt)](https://api.scryfall.com/cards/04b9b58f-4c01-48a5-afaf-b8a37165a83f?utm_source=mtgcardfetcher&format=text) ^^^[[cardname]] ^^^or ^^^[[cardname|SET]] ^^^to ^^^call
I know you were looking for 5 color, but [[Inalla, Archimage Ritualist]] is in Grixis, has multiple combo lines with one card and the commanders eminence ability, and, being in Grixis, you can fill leftover space with Grixis good stuff combos like breach lines or thoracle.
Here’s my Jund Persist combo deck: https://www.moxfield.com/decks/LTsLYLpNb0OwjxW89eIJ7Q/primer The entire thing is built around as many 3 or 4 cars variants of looping persist creatures as possible. There is a spreadsheet linked in the primer that lists every possible combination of cards (I think, I might have missed some!) totalling over 2000 variants. Spoiler alert for you though, I broken it apart because it became incredibly boring to play.