i have a kaboom/erratic deck that works quite well, but its mono red... and you're route i really like the kindle the carnage idea/shapeshifter idea...
you may also want to run volrath's shapeshifter though, you may also want to consider that aetherplasm thing that you can put a creature from your hand into play, or maybe fold into aether.. if you have enough mana (and maybe cheap spells)..
although a r/u version would be insane...
if you're interested, my monored worked insane.. you might be able to use some parts of it..
basically it ran
pulverize
cave-in
pyrokensis
slice and dice
fireblast
for "free burn"
also ran the mercadian masks red depletion land
4 scroll racks
4 pyromancy
3-4 kaboom
4 erratic explosion
blinkmoth infusion
autochon worm
draco
anything that was 11+
it had the ability to kill on turn 3.. with no mana accel..
t1:mountain, wait..
t2:mountain, wait..
t3:mountain, erratic explosion revealing draco, sac 2 lands for fireblast

.
and any cards you have in hand you can scroll rack back or pyromancy.
if you're doing a r/u build... a "i can get awesome creatures for nothin/ aka. erratic explosion for the win"
you may want to change some things:
i took a look at riptide shapeshifter.... he's pretty bad..
im thinking volrath's shapeshifter, unstable shapeshifter, etc.
shifty doppelganger might be a good one shot, pay 3, attack with a polar kraken, fling him, game...
sensei's top should probably be replaced with scroll rack..
bloodshot cyclops and/or fling should find its way in..
there should also be some mana acceleration..
maybe 4x saprazzan skerry and
4x sandstone needle... and most likely 4 izzet signets..
for a turn 2 show and tell/erratic/ or something equally brutal..
you could even run that awful artifact timesifter for extra turns..
you may also need something to give these monsters haste..
4 erratic
4 kaboom
4 pyromancy
volrath's shapeshifter
unstable shapeshifter
Clone
Shift doppelganger
Show and tell
creatures of choice:
flowstone hellion, Polar Kraken, Leviathan, grozoth, krosan colossus, eater of days, autochon wurm, plated slagwurm, iname as one over grozoth, hypnox, living inferno, silvos, symbiotic, verdant force, cabal archon, avatar of woe..
and for good mana i'd run
4 saprazzan skerry
4 sandstone needle
4 izzet signet
heres a variant i've been tinkering with..
deck;;
4 autochton wurm
4 hypnox
3 iname as one
1 grozoth
1 blazing archon
1 serra avatar
1 silvos
1 krosan colossus
4 volrath's shapeshifter
4 show and tell
4 shifty doppelganger
4 erratic explosion
4 pyromancy
3 kaboom
2 mountain
3 island
4 volcanic island
4 saprazzan skerry
4 sandstone needle
4 izzet signet
i was thinking about replacing kaboom with fling... as all i'd need is two turns and one attack...
even thought the depletion lands are really suicidal, i dont think it matters..
but with 4 signets... it might be helpful to run more "solid lands"
maybe using just 2 saprazzan, 2 sandstone...
here are some early games.. i'm gonna try this on mws...
turn 1 sandstone
turn 2 island, show and tell, autochton
turn 3 erratic revealing hypnox
turn 1:mountain
turn 2:island, signet
turn 3: show and tell silvos (holding fling)
turn 4: attack with silvos, play shifty doppel (holding fling)
turn 5: use shifty/fling/attack.
turn 1: sandstone
turn 2: sandstone, play signet
turn 3: mountain, tap all for 6 mana,... play 2 show and tells