Back in the early days of Slivery, the Slivers
granted their abilities to ALL Slivers, and
Sliver vs Sliver decks created quite a
conundrum. Every Sliver you played strengthened
your own team, but also your opponents, and the
only solution was to simply have the most
Slivers on the board. Sliver Overlord was
perhaps a means to break such a stalemate. It
has a sizeable body; big enough to safely block
most Slivers. It confers no additional benefit
to other Slivers on the board, so you don't have
to worry about what your opponent will gain. It
can also bolster your own army in two ways-- by
tutoring for any other Sliver in your deck (and
thus finding you any ability to grant your team
that you may need in the current situation), and
by forcibly conscripting your opponents' Slivers
out from under them. The second ability is only
useful in a mirror match, or if your opponent
using Changelings, or something like Act of
Treason (and not even then, really, because
they'd just steal the Overlord anyway). But the
first is terribly useful, as it guarantees you
the ability to put out more Slivers every turn.
This was the second legendary Sliver printed,
and it's interesting to note how well his
ability works against other Sliver decks,
especially the most high-value target: Sliver
Queen. As far as advancing their game plan, he's
less of a necessary cog (if you have a 7/7
creature, you're in a good position to win even
without searching for more) and more of the card
you go to when you want to make your Slivers
have a very specific set of abilities just for
the heck of it. But he does that very well.
Today's card of the day is Sliver Overlord
which is a five mana and five color 7/7
Legendary that for three mana can gain control
of a target sliver or for three mana can search
your library for a sliver and add it to your
hand. This is a solid support card for a
five color sliver deck supported with the right
lands plus Green's mana fixing slivers.
Searching for any sliver as needed is very
powerful and with other effects added to a 7/7
body this becomes a game ending threat as well,
particularly in Commander. This may not be
as impressive as Sliver Queen's low cost token
production, but is is a powerful card and a
popular choice for sliver decks in formats that
allow it.
In a Limited format with this it is a very
difficult card to utilize as it has five colors
and requires other slivers to be more than a
7/7, though the second effect could actually see
use. In Sealed it can be built around if
there is enough support, but running the deck
around it is difficult at best with anything
less than an excellent draw. For Booster
it has value as a rare draft, though slivers are
popular and drawing a pool for it depends on the
pod.