So, what was "The Rule" for Invasion-only Draft?
Upon further reflection, while other formats seem to have a specific "Rule" for what to draft (as defined by certain Pros), Invasion doesn't seem to have one. Hmm.
UBR was "the rule" for invasion. The power of: FTK, DD, Removal (terminate) and serious drawing power (FoF, Repulse, Exclude) made it the most powerful possible combination.
Often it would be played depending on what you opened... such as Pyre zombie made it BRu, while playing UB in invasion, then opening FTK or Jilt would make it UBr.
Not a "rule" but a guide, anyway.
Are we talking straight invasion or invasion block?
Anywaym the rule for the block was to have at least 2 of RBU, if not all three. Which two could be flexible, and all permutations were reasonable, as BR was solid in invasion and amazing in planeshift, BU was amazing in invasion and solid in planeshift, and UR was otherworldy in apocalypse while being solid thanks to individual card strength in the other two sets.
All 3 of BRU was far too rigid a rule, and often would lead to mana problems and/or dead apocalypse picks.
URW and URG were my personal favourites, although I went UBR when it was open (I usually would have one colour I could opt out of in apocalypse if need be). UBG was popular with many others, the idea being to draft UB for 2 sets (and only green when there was no U/B), then pick up UG and UB gold power cards in apocalypse.
i feel with 1 invasion, 2 apoc, or 1 of each white/red/black was just crazy, 2-3 putrid warriors, 2-3 goblin legionairres, so many bombs, honor guards, verdicts, terminates, and red burn, ftk, captains maneuver, shivan zombie, sinister strength, black removal, the white desciple, i mean the list just goes on and on, and you could consistently get the good cards for it, it had great removal, solid creatures, big bombs, good size creatures, good mana curve, overall very goo combinations