There's already a Sliver that grants other
Slivers haste, but that one is a 1/1 for (1R),
and gives it to your opponents' Slivers too.
Honestly, I haven't seen a whole lot fo Sliver
vs. Sliver matchups in my day-- people talk
about it like they expect it to come up, but
outside of certain Standard formats where
Slivers have proven viable, it just doesn't
really happen. The only real exception was Time
Spiral/Lorwyn Standard, where a Sliver player
would occasionally power up his opponent's
Changelings, but most Changelings weren't even
good enough for it to make a difference.
Haste is a non-stacking ability, and not a
particularly important one to have at that.
There's no real need to run both this AND Heart
Sliver, and since Heart is cheaper I imagine
most people will just keep using that one. You
might choose Blur if you know your friends also
have Sliver decks, or if your deck's curve is
kind of clogged at the two-mana slot, or if you
just don't have access to cards as old as Heart
Sliver, but otherwise this one is easy to skip.
Cards that grant haste to all your creatures
have always been a lot more powerful than they
look. Concordant Crossroads and Fires of
Yavimaya have tournament pedigree, and Fervor
and Emblem of the Warmind have been making an
impact in casual settings since they were
printed. While Blur Sliver is obviously more
fragile than any of those cards, you have to
take into account that a lot of the creatures it
will be improving will also be getting other
boosts of various kinds. If you can keep your
Blur Sliver alive, there are a lot of decks that
will simply fold to a Megantic Sliver with haste
(worse if you have other Slivers you've managed
to keep alive).
Today's card of the day is Blur Sliver which is
a three mana Red 2/2 that gives your slivers
Haste. The effect isn't new to slivers, though
of the four it is the first to only benefit
slivers you control. The mana cost is
reasonable, even if Heart Sliver as a two mana
1/1 comes into play earlier, and is a strong
benefit alongside Manaweft or Hive Stirrings.
While not the automatic inclusion Heart Sliver
had been, this is still a solid addition to a
Standard legal sliver build and will see play.
In Limited this is at worst a 2/2 with Haste
for three, which is playable, and at best a very
aggressive threat in a tribal theme. With
options of First Strike and +2/+0 in color and
like this are also at non-rare slots the
potential for even mono-Red slivers to be a
playable theme. Haste also benefits Manaweft and
Hive Stirrings and there is really no drawback
to running Blur in the format. Depending on the
pack in Booster this can be a second or third
pick, though it is quite likely to be passed a
few times as Haste is only situational and can
be somewhat underestimated. In Sealed this can
easily be included in any Red build using
slivers and should only be sidedecked when there
are few or no slivers and that slot in the mana
curve is adequately represented.