There are two renegade army lists, each with it's own upsides and downsides.
IA13 has the "generic renegades", and the Siege of Varks has the other one.
Pick the varks one, its better for the style you are after
Only varks has the ordenace tyrant, who is the artillery expert-very krieg. its even more mind boggling with the "Purge"
FoC from varks, where your entire army can be nothing but the command squad, and from there on spam nothing but artillery, not even troops, just cannons. (who will also cause difficult terrain to be left in the wake-for lolz)
They also have the "Unending Host"
FoC in varks, also very krieg. (and while not very tested, its possibly
OP as feth in levels that make gladius and daemon summoning drool in envy of how much free stuff you get.)
You can read here to have a general idea of what you have to look for:
http://1d4chan.org/wiki/Warhammer_40,000/Tactics/Renegades_and_Heretics%287E%29#Vraks_Renegade_Unending_Host
Renegades in general is a very brutal army. you'll need tons of models, as part of the concept is that everything is so godamn cheap its criminal. (for example-sentinels may not be much-but heavy flamer sentinels at 20 points!?)
Purge artillery spam versus Unending Host will quite possibly be the most absurd matchup possible in the game. "Carpet bomb ALL the things!", "Replace ALL the minions!"