What are all the ways to improve the total for a death saving throw?

For instance, the bless spell allows you to add 1d4 to any saving throws you make during the duration.

• I'm only interested in methods from official, 1st-party products.
• UA playtest content is not all that useful for me, but I know a lot of tables play with UA so it wouldn't hurt to have it in an answer.
• Granting advantage is less useful than direct modifiers, but again it wouldn't hurt to have it in the answer.

Anything that improves the total for a death save is good info.

What ways (other than advantage) are there to improve the total for a death saving throw?

For instance, the bless spell allows you to add 1d4 to any saving throws you make during the duration.

• I'm only interested in methods from official, 1st-party products.
• UA playtest content is not all that useful for me, but I know a lot of tables play with UA so it wouldn't hurt to have it in an answer.

(Granting advantage is less useful than direct modifiers to the roll, but it's still useful to know. However, that information is already covered by another question: How else can I get Advantage on Death Saving Throws? Therefore, advantage is outside the scope of this question.)

Bless allows you to add 1d4 to any saving throws you make during the duration, what other ways are there to increase death saves?

What are all the ways to improve the total for a death saving throw?

For instance, the bless spell allows you to add 1d4 to any saving throws you make during the duration.

• I'm only interested in methods from official, 1st-party products.
• UA playtest content is not all that useful for me, but I know a lot of tables play with UA so it wouldn't hurt to have it in an answer.
• Granting advantage is less useful than direct modifiers, but again it wouldn't hurt to have it in the answer.

Anything that improves the total for a death save is good info.