Priestess and Angel both need a power/toughness, and they probably shouldn't be legendary. Technically, they aren't actual Timelords either, and there aren't many appropriate substitute names. Typing could be changed to Artifact Creature - Construct. Angel also needs a higher cost, I think, while the main Timelords could have a cost reducing ability in place of the line about preventing damage (as protection already does that for damage against them, and damage dealt by them would only be relevant to Sandaion).
Suggested text/mechanic fixes:
"If you control no creatures, you may cast Timelord Priestess without paying its mana cost.
{T}: Sacrifice Timelord Priestess: Search your library for an Angel creature card with converted mana cost 10, reveal that card, and put it into your hand. Then shuffle your library." (Currently, there are exactly zero printed Angels with a CMC of 10.)
"When Timelord Angel dies, if it was dealt combat damage, return each creature to its owner's hand." (This is as close an equivalent to "destroyed by battle" as I'm aware. The ability would be even more broken for the current cost if it triggered upon any death as other abilities often do.)
"(optional ability to reduce mana cost)
At the beginning of your upkeep, shuffle Metaion, the Timelord into its owner's library.
Metaion can block any number of creatures.
When Metaion attacks or blocks, return each other creature to its owner's hand, then Metaion deals 1 damage to each opponent for each of those creatures. "
The only capitalized words in card text are card names, card types, and the first word of every line.