You can get four random numbers from 1-6 from this link.

https://www.random.org/integers/?num=4&min=1&max=6&col=5&base=10&format=html&rnd=new

FAQ:

Q: Can I create a token instead of a creature?
A: Sure, why not.

Q: I'm not sure what's included in "In rules text". Can I use "a" for "one"? Can I use "double" for 2? Can I use either numerals or spell it out?
A: Yes, any of that's fine.

Q: Can I create another card type instead?
A: I can't see how.

Q: But if I can think of something?
A: Sure, knock yourself out.

Q: Actually, this sounds a bit hard. Can I just use three numbers?
A: Yeah, that sounds fun too.

Q: Wait, you used a TRUE random number site? Can I use a different site if it only uses pseudorandom numbers.
A: Yes, that's completely fine. Random.org just happens to be the top hit on google. Get 4d6 from a dice rolling site.

Q: Actually, I'd like it to be harder. Can reQ:ire the numbers to be in order? 1 to 6 is a bit sensible, can I use 0 to 8?
A: Sure.

Q: How about -2 to 17?
A: If you like.

Q: You seem a lot less precise than you often are...?
A: Some challenges I think "restrictions breed creativity", and throwing back attractive near-misses to come up with something that fits produces more interesting cards. Other challenges I think the main work is in providing a place to get started, and if people want to wander off from there, that's all to the good.

Q: You wrote a lot of words for this, when you could have just said "...or something along those lines". Are you putting something off? Do you wish you'd spent those words on something more productive?
A: No comment.

To give you the idea, I rolled 3,6,6,5 and made Demon of Insanity

Created Harbinger of Ulamog. Numbers were 2, 5, 6, and 2.

Added Flame-Kin Foreguard with 5, 5, 1, 1.

Oh, as an aside. Jack couldn't think of something that easily incorporates 4 numbers besides creatures. But Planeswalkers do. In fact, you're better rolling 5 times if you want one of them (and rearranging the middle 3 in numerical order for it all to make more sense.) Also, an instant or a sorcery that produces a creature token, or some trick akin to Symbiosis makes sense in my mind, too.

Added Educated Quanar with 4, 3, 6, 6.

Oh yeah, the planeswalker-specific version would be interesting. So would a "generate a card with these three numbers in the rules text".

­Essence of Volatility with 6,6,1,6

­Wall Between Life and Death with 3, 1, 6, 4

Made Boreal Forest Fire off of Jack's suggestion to put three of the numbers in the text. Accidentally added an extra number three without realizing my mistake. Ah well.

­Nervous Looter with 3, 1, 2, 3.

­Headless Butcher with 2, 1, 2, 2

­Learning Cub with 6,2,3,6.

I moved the numbers around this time, I had too many 6 power or 6 toughness cards.

When I put a number in the rules text I keep redesigning it and forgetting the number. But this time it went somewhere interesting even if ridiculous.

­Hot Coal Elemental with 3, 6, 3, 6.