25% may be ok for the unupped version, but 50% is a bit too high I think.
On the other hand, 15% / 25% is a little on the low side, but 25% / 25% gives little reason to upgrade...
maybe 20% / 33% would be good (1/5 and 1/3 respectively)
Otherwise, this seems like a pretty cool card. Its a single target half SoFr. Which is nice since there is no other way to provide either of SoFr two main effects as of right now... (and I'm generally in favor of mitigating the currently rather heavy impact of shards on the game at present)