Turn 2 - no this is where it really gets bloody.
Teleports - I screwed up here by forgetting about my avatar until GROOV3R had placed his 2 terminator fms - we should have rolled off (as both have an SR5), then taken turns. Anyway, we played it as is.
Both terminator fms teleport to the east of the mech guardians, out of support range of the blitz guardians (though I forgot they were on overwatch, doh!). 2BMs taken.
With a mighty bellow and a gleeful twinkle in his eye, the Avatar pops into existence between the mech guardians and the terminators.
Strategy roll - Marines!
Unsurprisingly, the terminators call a coordinated assault on the Avatar and mech guardians. however, because the guardians had their waveserpents between them and the terminators, only a few got into BtB with guardians (and 2 or 3 on the Avatar), losing their +1EA MW CC attacks. Farseer countercharged into BtB with the closest terminator.
Guardians and Avatar roll high and terminators roll low, with 3 terminator stands lost for 1 waveserpent (the avatar soaked up most of the hits with his RA, no DC lost!). Resolution saw another 2 terminator stands lost, and the broken fm of 3 ran away into a nearby wood.
Cool!
Realising my windriders were only a Princeps' finger twitch away from being a BBQ, they sustained fire at the assault marines (SC), taking out another stand!
In response, the warhounds let loose their volcano cannons and destroyed every single one of the (several times over I think). No demure Guardian ladies for these heroes back on the craftworld!
Nightspinners 2 sustain at the assault marines (SC), causing another 2 or 3 BMs, but no casualties.
Then, the sky rips apart and the orbital bombardment lands on my poor blitz guardians! 2 orbital barrage templates later and surprisingly, only 3 guardians are atomised (still enough to suppress the hvy wpns teams, crap).
Can't remember precisely what the order is next, but the lander arrives, scattering slightly to the E of the mech guardians, unloading the assault marines, devastators and tac detachment with predators. Rolling his eyes and wondering what he's done to get all the bad luck, the farseer waits for the attack.
Which isn't long coming, as the assault marines engage in CC, targeting the back of the formation (but still outside support range of the blitz guardians). Avatar rubs his molten hands together in joy and barges through the guardians to BtB 2 assault marine stands. Again rolling high for the guardians and low for the marines, 2 (or 3, can't remember) marine stands are scythed down for 1 guardian loss, with the avatar soaking up most of the hits. Marines are wiped out on resolution.
Dark reapers decide to get in on the action and double towards the tac detachment, causing no hits but placing a crucial BM and getting into support range.
Avatar then retains and drags the mech guardian fm (somewhat unwillingly, "haven't we done enough" they cry) into an engage with the Tac detachment. Avatar manages to BtB the front row of tac stands, with waveserpents, then guardians in FF range. Tacs dish out a decent no. of hits, all of which are allocated to the Avatar then waveserpents then Avatar again, only resulting in 1 waveserpent crashing to the ground. In return a whole slew of tacs get squashed/ sliced. Support fire from the lander causes a couple of hits, which are, again, soaked up by the Avatar for no loss. Dark reapers enjoy the show so much they do absolutely bugger all. When the dust clears, nothing is left from the Tac detachment
At that point, with largely intact formations (less the nightspinners, the lovely little GROOV3R baits that they are) vs. a massively reduced Marine army, GROOV3R decides to call it a day.
How bloody was that?