You hopefully already have your color, making Sol Ring far better
Firstly, white cares enough about enchantments that reducing the costs on permanents instead of just creatures can pay dividends
Karametra's Acolyte CMC: 4 1/4 stats aren't great for a four-cost creature, but that four toughness is just high enough to survive the common red "Lightning Bolt" removal or withstand a few -1/-1 counters
Basic lands come in six types, with each of the six producing a different type of mana when tapped: Plains produce white mana, Islands produce blue, Swamps produce black, Mountains produce red, Forests produce green, and Wastes produce colourless (and are much, much less common than the other five, having only appeared in one set)
Here is what that would look like: You Declare Najeela as an attacker and attack an opponent unable to block or kill her