The short version of that, with TMW, is to make a meta group that has a cooldown icon for each ability + conditions, in order of priority. Then you make a separate group with one icon that displays that displays the meta group.
Here's a sample Meta group:
Code:
^1^T^SPoint^T ^Sy^F-8092412304425110 ^f-46^Spoint ^STOPLEFT^SrelativePoint ^STOPLEFT^Sx ^F8561556961362511^f-46 ^t^SRole^N1 ^SColumns^N20 ^SGUID^STMW:group:1Jzccn8IVwce ^STree1^b ^SIcons^T ^N1^T ^SType^Scooldown ^SName^SSearing~`Totem ^SFakeHidden^B ^SConditions^T ^N1^T ^SType^SBUFFDUR ^SOperator^S<= ^SLevel^N3 ^SName^SSearing~`Flames ^t^N2^T ^SType^STOTEM1 ^t^Sn^N2 ^t^SEnabled^B ^t^N2^T ^SType^Scooldown ^SName^SLightning~`Bolt ^SFakeHidden^B ^SConditions^T ^N1^T ^SType^SBUFFSTACKS ^SLevel^N5 ^SName^SMaelstrom~`Weapon ^t^Sn^N1 ^t^SEnabled^B ^t^N3^T ^SType^Scooldown ^SName^SStormstrike;~`Stormblast ^SFakeHidden^B ^SConditions^T ^Sn^N1 ^t^SEnabled^B ^t^N4^T ^SType^Scooldown ^SName^SFlame~`Shock ^SFakeHidden^B ^SConditions^T ^N1^T ^SType^SBUFFDUR ^SChecked^B ^SOperator^S> ^SName^SUnleash~`Flame ^t^N2^T ^SType^SDEBUFFDUR ^SChecked^B ^SUnit^Starget ^SName^SFlame~`Shock ^SPrtsBefore^N1 ^SAndOr^SOR ^t^N3^T ^SType^SSPELLCD ^SPrtsAfter^N1 ^SOperator^S> ^SLevel^N5 ^SName^SUnleash~`Elements ^t^Sn^N3 ^t^SEnabled^B ^t^t^SName^SEnh~`Meta ^STree3^b ^t^N70307^S~`~| ^Sgroup^N3 ^^
And a sample display group/icon for it:
Code:
^1^T^SPoint^T ^Sy^F4691247339929549 ^f-45^Spoint ^SLEFT^SrelativePoint ^SLEFT^Sx ^F8678830542684579^f-46 ^t^SRole^N1 ^SColumns^N1 ^SGUID^STMW:group:1JzcdAKnJUT4 ^STree1^b ^SIcons^T ^N1^T ^SType^Smeta ^SIcons^T ^N1^STMW:group:1Jzccn8IVwce ^t^SEnabled^B ^t^t^SName^SEnh~`Display ^STree3^b ^t^N70307^S~`~| ^Sgroup^N4 ^^
I implemented (roughly) the first four abilities listed in the Icy-Veins priority queue,
here, for single-target abilities. You can add more by simply continuing down the line in the meta group and figuring out the appropriate conditions.
You can get similar or better behavior from clcEnh or Nemo (if you want a single icon display), or EnhaPrio or Hekili (my addon). End shameless plug.