If you use this in the late game, you can easily build a strong board and overwhelm your opponent
Most of these reprints are decently valuable too, although admittedly not quite enough to break even
The Half Star Layer does not
In that case, the attacking creatures it was blocking won't gain trample even though the blocking creature is destroyed
Spells with this kind of effect are becoming increasingly problematic in Magic - if seven mana additional turn spells like Nexus of Fate and Alrund's Epiphany can get banned, it's easy to see why Time Walk is so scary
The more mana you have, the more spells you can play during a turn cycle to prevent threats from hitting the table, taking them off the battlefield, or simply stealing them for yourself