Make it so you either have PoS for a certain amount of coin 100 to 1000 coins to protect the blockchain or you have so much coin that you can send a fee in that would burn it into boosting PoS.
I really like that idea. Being able to burn coins somehow to give a better reward to whoever produces the next block.
If you coordinated the event, you could buy a crap load of coins, then for the next 500 blocks increase the reward by 50 coins per block and let everyone know about it.
Or, you could have a lottery, saying that you promise to burn 2500 OPAL sometime between now and next Tuesday, which gets people installing wallets and staking coins trying to earn the stake reward if they get that block
Or, [insert your idea]