"...the details of phasing are fairly arbitrary and make no sense if you think about them. Phasing out does trigger "leaves play" abilities, but phasing in does not trigger "comes into play abilities." So it leaves play but doesn't come into play? Huh?! We've decided that was just too counter-intuitive to leave in place, so we're cleaning things up. Phasing will no longer trigger leaves play abilities. (The other potential change -- having phasing trigger "comes into play" abilities -- might have had a little better flavor, but it's way too big of a functional change to way too many cards so we're not doing that.) This change will be part of the Ravnica update to the Comp Rules, so it will go into effect on approximately October 1st."
-Randy Buhler, 8/04/05
When Mirage first came out, the ability Phasing seemed new and interesting. Making 'eee-yownk!' sounds when our forced-phasing creatures slid out of play and into play, getting 'huge' discounts for giant things like Sandbar Crocodile and Merfolk Raiders. Eventually, however, we all realized that forced phasing was a disadvantage-- a HUGE disadvantage. As the year boiled by, we came to discover that Phasing had three 'good' qualities, and one good use on creatures.
The creatures that had the ability to phase out as an instant have proven themself over time. Teferi's Honor Guard and Frenetic Efreet are classic creatures for their ability to avoid death at a rate of fifty percent or better.
The other three uses of Phasing did not center on the creatures, but the enchantments and instants that phased creatuers out.
When Mirage first came out, the timing of Phasing was not very clear. Most people chose when to untap or when to phase things in or out. Thus, the first 'abuse' for Flanking was Seasinger or Ray of Command permanantly stealing a creature. Take a creature, phase it out, and at the end of turn it's not there to hand back! Now let's Seasinger a creature, then have the creature phase out at the beginning of my turn before I untap Seasinger-- Now the creature can't go back to you, because it's not there, and it ALSO phases into play under the control of the player it left. Sixth edition changed this little abuse, and made Phasing slightly less ill-defined.
Early on, players realized that Phrexian War Beast was quite good. Blue players had fits with a second-turn Beast, and looked for a good solution... and that Teferi's Curse was an excellent solution, both reducing the damage and eliminating your opponent's board position simultaneously made the three mana beatstick quite manageable. As time went on, more Leaves Play abilities were put forward, some causing massive amounts of lifegain, such as Soulgorger Orgg, or granting extra turns, such as Wormfang Manta. Others that used this effect of phasing to its full extent were printed as recently as Darksteel: Sundering Titan. The avoidance of negative comes into play abilities and abuse of leaves play ability caused this to be the best use of the cards that grant Phasing, whether forced or not. Sadly, Buhler has states that this was too 'confusing,' once again killing a use of Phasing that had existed for many, many years.
The final good use of Phasing only interacts with one card, and this was good enough to give rise to a very powerful monoblue deck-- Nevinyrral's Disk and Reality Ripple/Vision Charm. After activating the Disk but before it resolves, phase the disk out and have it destroy all creatures, enchantments, and artifacts-- other than itself. Counter anything that you need to, and repeat the rippledisking as necessary. This has not yet been removed from Magic, but if the Disk gets reprinted, it's a 2:1 odds-on bet that the cost will be "1, T, Sacrifice Nevinyrral's Disk:" and not "1, T:" as it currently is written.
Phasing, some of us know you well. However, slowly but surely, Wizards of the Coast brings you to your knees. If drastic changes to older abilities is par for the course, possibly some of your other unused abilities will get boosts instead of repressions.
Phasing, the most legitimatly hated mechanic in Magic, and one of the oddest implementations of rules, the ability that is about to slightly die even more, I Salute You!