Whats funny is I didnt even realize Bruvac was a character from Ravnica, I guess it's decidedly Dimir ability and absence of any surrounding Azorius imagery led me to believe they were just some guy with a big hat
In Visions (February 1997), islandwalk's (as an example) reminder text said, "If defending player controls any islands, this creature is unblockable." In Classic Sixth Edition (April 1999), the reminder text said, "This creature is unblockable if defending player controls an island." Then, with Urza's Destiny (June 1999), this was minusculely changed to "This creature is unblockable as long as defending player controls an island." This is how the reminder text has appeared since, with the exception of Portal Three Kingdoms (July 1999) that temporarily changed it to, "If defending player has an island in play, CARDNAME can't be blocked." Landwalk has been in a lot of sets through Magic's history
Lumbering Worldwagon Lumbering Worldwagon is a pretty substantial threat
So yeah, Tinybones, Trinket Thief is very powerful
Even if one isn't playing those colors or doesn't have Channel-Fireball, a Black Lotus can give a nice mana bonus for a player, allowing them to play powerful cards in the early game